Source code:
SQLite is a C library that provides a lightweight disk-based database that doesn’t require a separate server process and allows accessing the database using a nonstandard variant of the SQL query language. Some applications can use SQLite for internal data storage. It’s also possible to prototype an application using SQLite and then port the code to a larger database such as PostgreSQL or Oracle.
The sqlite3 module was written by Gerhard Häring. It provides an SQL interface compliant with the DB-API 2.0 specification described by
, and requires the third-party
library.
This is an
. If it is missing from your copy of CPython, look for documentation from your distributor (that is, whoever provided Python to you). If you are the distributor, see
Requirements for optional modules
.
This document includes four main sections:
teaches how to use the sqlite3 module.
describes the classes and functions this module defines.
details how to handle specific tasks.
provides in-depth background on transaction control.
See also
The SQLite web page; the documentation describes the syntax and the available data types for the supported SQL dialect.
https://www.w3schools.com/sql/
Tutorial, reference and examples for learning SQL syntax.
- Database API Specification 2.0PEP written by Marc-André Lemburg.
Tutorial
In this tutorial, you will create a database of Monty Python movies using basic sqlite3 functionality. It assumes a fundamental understanding of database concepts, including
and
.
First, we need to create a new database and open a database connection to allow sqlite3 to work with it. Call
to create a connection to the database tutorial.db in the current working directory, implicitly creating it if it does not exist:
importsqlite3con=sqlite3.connect("tutorial.db")The returned
object con represents the connection to the on-disk database.
In order to execute SQL statements and fetch results from SQL queries, we will need to use a database cursor. Call
to create the
:
cur=con.cursor()Now that we’ve got a database connection and a cursor, we can create a database table movie with columns for title, release year, and review score. For simplicity, we can just use column names in the table declaration – thanks to the
feature of SQLite, specifying the data types is optional. Execute the CREATETABLE statement by calling
:
cur.execute("CREATE TABLE movie(title, year, score)")We can verify that the new table has been created by querying the sqlite_master table built-in to SQLite, which should now contain an entry for the movie table definition (see
for details). Execute that query by calling
, assign the result to res, and call
to fetch the resulting row:
>>> res=cur.execute("SELECT name FROM sqlite_master")>>> res.fetchone()('movie',)We can see that the table has been created, as the query returns a
containing the table’s name. If we query sqlite_master for a non-existent table spam, res.fetchone() will return None:
>>> res=cur.execute("SELECT name FROM sqlite_master WHERE name='spam'")>>> res.fetchone()isNoneTrueNow, add two rows of data supplied as SQL literals by executing an INSERT statement, once again by calling
:
cur.execute(""" INSERT INTO movie VALUES ('Monty Python and the Holy Grail', 1975, 8.2), ('And Now for Something Completely Different', 1971, 7.5)""")The INSERT statement implicitly opens a transaction, which needs to be committed before changes are saved in the database (see
for details). Call
on the connection object to commit the transaction:
con.commit()We can verify that the data was inserted correctly by executing a SELECT query. Use the now-familiar
to assign the result to res, and call
to return all resulting rows:
>>> res=cur.execute("SELECT score FROM movie")>>> res.fetchall()[(8.2,), (7.5,)]The result is a
of two tuples, one per row, each containing that row’s score value.
Now, insert three more rows by calling
:
data=[("Monty Python Live at the Hollywood Bowl",1982,7.9),("Monty Python's The Meaning of Life",1983,7.5),("Monty Python's Life of Brian",1979,8.0),]cur.executemany("INSERT INTO movie VALUES(?, ?, ?)",data)con.commit()# Remember to commit the transaction after executing INSERT.Notice that ? placeholders are used to bind data to the query. Always use placeholders instead of
to bind Python values to SQL statements, to avoid
(see
How to use placeholders to bind values in SQL queries
for more details).
We can verify that the new rows were inserted by executing a SELECT query, this time iterating over the results of the query:
>>> forrowincur.execute("SELECT year, title FROM movie ORDER BY year"):... print(row)(1971, 'And Now for Something Completely Different')(1975, 'Monty Python and the Holy Grail')(1979, "Monty Python's Life of Brian")(1982, 'Monty Python Live at the Hollywood Bowl')(1983, "Monty Python's The Meaning of Life")Each row is a two-item
of (year,title), matching the columns selected in the query.
Finally, verify that the database has been written to disk by calling
to close the existing connection, opening a new one, creating a new cursor, then querying the database:
>>> con.close()>>> new_con=sqlite3.connect("tutorial.db")>>> new_cur=new_con.cursor()>>> res=new_cur.execute("SELECT title, year FROM movie ORDER BY score DESC")>>> title,year=res.fetchone()>>> print(f'The highest scoring Monty Python movie is {title!r}, released in {year}')The highest scoring Monty Python movie is 'Monty Python and the Holy Grail', released in 1975>>> new_con.close()You’ve now created an SQLite database using the sqlite3 module, inserted data and retrieved values from it in multiple ways.
See also
for further reading:
How to use placeholders to bind values in SQL queries
How to adapt custom Python types to SQLite values
How to convert SQLite values to custom Python types
How to use the connection context manager
How to create and use row factories
for in-depth background on transaction control.
Reference
Module functions
sqlite3.connect(database, timeout=5.0, detect_types=0, isolation_level='DEFERRED', check_same_thread=True, factory=sqlite3.Connection, cached_statements=128, uri=False, *, autocommit=sqlite3.LEGACY_TRANSACTION_CONTROL)
Open a connection to an SQLite database.
Parameters:database (
) – The path to the database file to be opened. You can pass ":memory:" to create an
SQLite database existing only in memory
, and open a connection to it.
timeout (
) – How many seconds the connection should wait before raising an
when a table is locked. If another connection opens a transaction to modify a table, that table will be locked until the transaction is committed. Default five seconds.
detect_types (
) – Control whether and how data types not
are looked up to be converted to Python types, using the converters registered with
. Set it to any combination (using |, bitwise or) of
and
to enable this. Column names take precedence over declared types if both flags are set. By default (0), type detection is disabled.
isolation_level (
| None) – Control legacy transaction handling behaviour. See
and
Transaction control via the isolation_level attribute
for more information. Can be "DEFERRED" (default), "EXCLUSIVE" or "IMMEDIATE"; or None to disable opening transactions implicitly. Has no effect unless
is set to
(the default).
check_same_thread (
) – If True (default),
will be raised if the database connection is used by a thread other than the one that created it. If False, the connection may be accessed in multiple threads; write operations may need to be serialized by the user to avoid data corruption. See
for more information.
factory (
) – A custom subclass of
to create the connection with, if not the default Connection class.
cached_statements (
) – The number of statements that sqlite3 should internally cache for this connection, to avoid parsing overhead. By default, 128 statements.
uri (
) – If set to True, database is interpreted as a URI with a file path and an optional query string. The scheme part must be "file:", and the path can be relative or absolute. The query string allows passing parameters to SQLite, enabling various
.
autocommit (
) – Control
transaction handling behaviour. See
and
Transaction control via the autocommit attribute
for more information. autocommit currently defaults to
. The default will change to False in a future Python release.
Return type:
Raises an
sqlite3.connect with argument database.
Raises an
sqlite3.connect/handle with argument connection_handle.
Changed in version 3.4: Added the uri parameter.
Changed in version 3.7: database can now also be a
, not only a string.
Changed in version 3.10: Added the sqlite3.connect/handle auditing event.
Changed in version 3.12: Added the autocommit parameter.
Changed in version 3.13: Positional use of the parameters timeout, detect_types, isolation_level, check_same_thread, factory, cached_statements, and uri is deprecated. They will become keyword-only parameters in Python 3.15.
sqlite3.complete_statement(statement)
Return True if the string statement appears to contain one or more complete SQL statements. No syntactic verification or parsing of any kind is performed, other than checking that there are no unclosed string literals and the statement is terminated by a semicolon.
For example:
>>> sqlite3.complete_statement("SELECT foo FROM bar;")True>>> sqlite3.complete_statement("SELECT foo")FalseThis function may be useful during command-line input to determine if the entered text seems to form a complete SQL statement, or if additional input is needed before calling
.
See runsource() in
for real-world use.
sqlite3.enable_callback_tracebacks(flag, /)
Enable or disable callback tracebacks. By default you will not get any tracebacks in user-defined functions, aggregates, converters, authorizer callbacks etc. If you want to debug them, you can call this function with flag set to True. Afterwards, you will get tracebacks from callbacks on
. Use False to disable the feature again.
Note
Errors in user-defined function callbacks are logged as unraisable exceptions. Use an
for introspection of the failed callback.
sqlite3.register_adapter(type, adapter, /)
Register an adapter
to adapt the Python type type into an SQLite type. The adapter is called with a Python object of type type as its sole argument, and must return a value of a
type that SQLite natively understands
.
sqlite3.register_converter(typename, converter, /)
Register the converter
to convert SQLite objects of type typename into a Python object of a specific type. The converter is invoked for all SQLite values of type typename; it is passed a
object and should return an object of the desired Python type. Consult the parameter detect_types of
for information regarding how type detection works.
Note: typename and the name of the type in your query are matched case-insensitively.
Module constants
sqlite3.LEGACY_TRANSACTION_CONTROL
Set
to this constant to select old style (pre-Python 3.12) transaction control behaviour. See
Transaction control via the isolation_level attribute
for more information.
sqlite3.PARSE_DECLTYPES
Pass this flag value to the detect_types parameter of
to look up a converter function using the declared types for each column. The types are declared when the database table is created. sqlite3 will look up a converter function using the first word of the declared type as the converter dictionary key. For example:
CREATETABLEtest(iintegerprimarykey,!willlookupaconverternamed"integer"ppoint,!willlookupaconverternamed"point"nnumber(10)!willlookupaconverternamed"number")This flag may be combined with
using the | (bitwise or) operator.
Note
Generated fields (for example MAX(p)) are returned as
. Use PARSE_COLNAMES to enforce types for such queries.
sqlite3.PARSE_COLNAMES
Pass this flag value to the detect_types parameter of
to look up a converter function by using the type name, parsed from the query column name, as the converter dictionary key. The query column name must be wrapped in double quotes (") and the type name must be wrapped in square brackets ([]).
SELECTMAX(p)as"p [point]"FROMtest;!willlookupconverter"point"This flag may be combined with
using the | (bitwise or) operator.
sqlite3.SQLITE_OK
sqlite3.SQLITE_DENY
sqlite3.SQLITE_IGNORE
Flags that should be returned by the authorizer_callback
passed to
, to indicate whether:
Access is allowed (SQLITE_OK),
The SQL statement should be aborted with an error (SQLITE_DENY)
The column should be treated as a NULL value (SQLITE_IGNORE)
sqlite3.apilevel
String constant stating the supported DB-API level. Required by the DB-API. Hard-coded to "2.0".
sqlite3.paramstyle
String constant stating the type of parameter marker formatting expected by the sqlite3 module. Required by the DB-API. Hard-coded to "qmark".
Note
The named DB-API parameter style is also supported.
sqlite3.sqlite_version
Version number of the runtime SQLite library as a
.
sqlite3.sqlite_version_info
Version number of the runtime SQLite library as a
of
.
sqlite3.threadsafety
Integer constant required by the DB-API 2.0, stating the level of thread safety the sqlite3 module supports. This attribute is set based on the default
the underlying SQLite library is compiled with. The SQLite threading modes are:
Single-thread: In this mode, all mutexes are disabled and SQLite is unsafe to use in more than a single thread at once.
Multi-thread: In this mode, SQLite can be safely used by multiple threads provided that no single database connection is used simultaneously in two or more threads.
Serialized: In serialized mode, SQLite can be safely used by multiple threads with no restriction.
The mappings from SQLite threading modes to DB-API 2.0 threadsafety levels are as follows:
SQLite threading mode
DB-API 2.0 meaning
single-thread
0
0
Threads may not share the module
multi-thread
1
2
Threads may share the module, but not connections
serialized
3
1
Threads may share the module, connections and cursors
Changed in version 3.11: Set threadsafety dynamically instead of hard-coding it to 1.
sqlite3.SQLITE_DBCONFIG_DEFENSIVE
sqlite3.SQLITE_DBCONFIG_DQS_DDL
sqlite3.SQLITE_DBCONFIG_DQS_DML
sqlite3.SQLITE_DBCONFIG_ENABLE_FKEY
sqlite3.SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER
sqlite3.SQLITE_DBCONFIG_ENABLE_LOAD_EXTENSION
sqlite3.SQLITE_DBCONFIG_ENABLE_QPSG
sqlite3.SQLITE_DBCONFIG_ENABLE_TRIGGER
sqlite3.SQLITE_DBCONFIG_ENABLE_VIEW
sqlite3.SQLITE_DBCONFIG_LEGACY_ALTER_TABLE
sqlite3.SQLITE_DBCONFIG_LEGACY_FILE_FORMAT
sqlite3.SQLITE_DBCONFIG_NO_CKPT_ON_CLOSE
sqlite3.SQLITE_DBCONFIG_RESET_DATABASE
sqlite3.SQLITE_DBCONFIG_TRIGGER_EQP
sqlite3.SQLITE_DBCONFIG_TRUSTED_SCHEMA
sqlite3.SQLITE_DBCONFIG_WRITABLE_SCHEMA
These constants are used for the
and
methods.
The availability of these constants varies depending on the version of SQLite Python was compiled with.
Added in version 3.12.
Deprecated since version 3.12, removed in version 3.14: The version and version_info constants.
Connection objects
classsqlite3.Connection
Each open SQLite database is represented by a Connection object, which is created using
. Their main purpose is creating
objects, and
.
Changed in version 3.13: A
is emitted if
is not called before a Connection object is deleted.
An SQLite database connection has the following attributes and methods:
cursor(factory=Cursor)
Create and return a
object. The cursor method accepts a single optional parameter factory. If supplied, this must be a
returning an instance of Cursor or its subclasses.
blobopen(table, column, rowid, /, *, readonly=False, name='main')
Open a
handle to an existing BLOB.
Parameters:table (
) – The name of the table where the blob is located.
column (
) – The name of the column where the blob is located.
rowid (
) – The row id where the blob is located.
readonly (
) – Set to True if the blob should be opened without write permissions. Defaults to False.
name (
) – The name of the database where the blob is located. Defaults to "main".
Raises:
– When trying to open a blob in a WITHOUTROWID table.
Return type:
Note
The blob size cannot be changed using the
class. Use the SQL function zeroblob to create a blob with a fixed size.
Added in version 3.11.
commit()
Commit any pending transaction to the database. If
is True, or there is no open transaction, this method does nothing. If autocommit is False, a new transaction is implicitly opened if a pending transaction was committed by this method.
rollback()
Roll back to the start of any pending transaction. If
is True, or there is no open transaction, this method does nothing. If autocommit is False, a new transaction is implicitly opened if a pending transaction was rolled back by this method.
close()
Close the database connection. If
is False, any pending transaction is implicitly rolled back. If autocommit is True or
, no implicit transaction control is executed. Make sure to
before closing to avoid losing pending changes.
execute(sql, parameters=(), /)
Create a new
object and call
on it with the given sql and parameters. Return the new cursor object.
executemany(sql, parameters, /)
Create a new
object and call
on it with the given sql and parameters. Return the new cursor object.
executescript(sql_script, /)
Create a new
object and call
on it with the given sql_script. Return the new cursor object.
create_function(name, narg, func, *, deterministic=False)
Create or remove a user-defined SQL function.
Parameters:name (
) – The name of the SQL function.
narg (
) – The number of arguments the SQL function can accept. If -1, it may take any number of arguments.
func (
| None) – A
that is called when the SQL function is invoked. The callable must return
a type natively supported by SQLite
. Set to None to remove an existing SQL function.
deterministic (
) – If True, the created SQL function is marked as
, which allows SQLite to perform additional optimizations.
Changed in version 3.8: Added the deterministic parameter.
Example:
>>> importhashlib>>> defmd5sum(t):... returnhashlib.md5(t).hexdigest()>>> con=sqlite3.connect(":memory:")>>> con.create_function("md5",1,md5sum)>>> forrowincon.execute("SELECT md5(?)",(b"foo",)):... print(row)('acbd18db4cc2f85cedef654fccc4a4d8',)>>> con.close()Changed in version 3.13: Passing name, narg, and func as keyword arguments is deprecated. These parameters will become positional-only in Python 3.15.
create_aggregate(name, n_arg, aggregate_class)
Create or remove a user-defined SQL aggregate function.
Parameters:name (
) – The name of the SQL aggregate function.
n_arg (
) – The number of arguments the SQL aggregate function can accept. If -1, it may take any number of arguments.
aggregate_class (
| None) –
A class must implement the following methods:
step(): Add a row to the aggregate.
finalize(): Return the final result of the aggregate as
a type natively supported by SQLite
.
The number of arguments that the step() method must accept is controlled by n_arg.
Set to None to remove an existing SQL aggregate function.
Example:
classMySum:def__init__(self):self.count=0defstep(self,value):self.count+=valuedeffinalize(self):returnself.countcon=sqlite3.connect(":memory:")con.create_aggregate("mysum",1,MySum)cur=con.execute("CREATE TABLE test(i)")cur.execute("INSERT INTO test(i) VALUES(1)")cur.execute("INSERT INTO test(i) VALUES(2)")cur.execute("SELECT mysum(i) FROM test")print(cur.fetchone()[0])con.close()Changed in version 3.13: Passing name, n_arg, and aggregate_class as keyword arguments is deprecated. These parameters will become positional-only in Python 3.15.
create_window_function(name, num_params, aggregate_class, /)
Create or remove a user-defined aggregate window function.
Parameters:name (
) – The name of the SQL aggregate window function to create or remove.
num_params (
) – The number of arguments the SQL aggregate window function can accept. If -1, it may take any number of arguments.
aggregate_class (
| None) –
A class that must implement the following methods:
step(): Add a row to the current window.
value(): Return the current value of the aggregate.
inverse(): Remove a row from the current window.
finalize(): Return the final result of the aggregate as
a type natively supported by SQLite
.
The number of arguments that the step() and value() methods must accept is controlled by num_params.
Set to None to remove an existing SQL aggregate window function.
Raises:
– If used with a version of SQLite older than 3.25.0, which does not support aggregate window functions.
Added in version 3.11.
Example:
# Example taken from https://www.sqlite.org/windowfunctions.html#udfwinfuncclassWindowSumInt:def__init__(self):self.count=0defstep(self,value):"""Add a row to the current window."""self.count+=valuedefvalue(self):"""Return the current value of the aggregate."""returnself.countdefinverse(self,value):"""Remove a row from the current window."""self.count-=valuedeffinalize(self):"""Return the final value of the aggregate. Any clean-up actions should be placed here. """returnself.countcon=sqlite3.connect(":memory:")cur=con.execute("CREATE TABLE test(x, y)")values=[("a",4),("b",5),("c",3),("d",8),("e",1),]cur.executemany("INSERT INTO test VALUES(?, ?)",values)con.create_window_function("sumint",1,WindowSumInt)cur.execute(""" SELECT x, sumint(y) OVER ( ORDER BY x ROWS BETWEEN 1 PRECEDING AND 1 FOLLOWING ) AS sum_y FROM test ORDER BY x""")print(cur.fetchall())con.close()create_collation(name, callable, /)
Create a collation named name using the collating function callable. callable is passed two
arguments, and it should return an
:
1 if the first is ordered higher than the second
-1 if the first is ordered lower than the second
0 if they are ordered equal
The following example shows a reverse sorting collation:
defcollate_reverse(string1,string2):ifstring1==string2:return0elifstring1<string2:return1else:return-1con=sqlite3.connect(":memory:")con.create_collation("reverse",collate_reverse)cur=con.execute("CREATE TABLE test(x)")cur.executemany("INSERT INTO test(x) VALUES(?)",[("a",),("b",)])cur.execute("SELECT x FROM test ORDER BY x COLLATE reverse")forrowincur:print(row)con.close()Remove a collation function by setting callable to None.
Changed in version 3.11: The collation name can contain any Unicode character. Earlier, only ASCII characters were allowed.
interrupt()
Call this method from a different thread to abort any queries that might be executing on the connection. Aborted queries will raise an
.
Register
authorizer_callback to be invoked for each attempt to access a column of a table in the database. The callback should return one of
,
, or
to signal how access to the column should be handled by the underlying SQLite library.
The first argument to the callback signifies what kind of operation is to be authorized. The second and third argument will be arguments or None depending on the first argument. The 4th argument is the name of the database (“main”, “temp”, etc.) if applicable. The 5th argument is the name of the inner-most trigger or view that is responsible for the access attempt or None if this access attempt is directly from input SQL code.
Please consult the SQLite documentation about the possible values for the first argument and the meaning of the second and third argument depending on the first one. All necessary constants are available in the sqlite3 module.
Passing None as authorizer_callback will disable the authorizer.
Changed in version 3.11: Added support for disabling the authorizer using None.
Changed in version 3.13: Passing authorizer_callback as a keyword argument is deprecated. The parameter will become positional-only in Python 3.15.
set_progress_handler(progress_handler, n)
Register
progress_handler to be invoked for every n instructions of the SQLite virtual machine. This is useful if you want to get called from SQLite during long-running operations, for example to update a GUI.
If you want to clear any previously installed progress handler, call the method with None for progress_handler.
Returning a non-zero value from the handler function will terminate the currently executing query and cause it to raise a
exception.
Changed in version 3.13: Passing progress_handler as a keyword argument is deprecated. The parameter will become positional-only in Python 3.15.
set_trace_callback(trace_callback)
Register
trace_callback to be invoked for each SQL statement that is actually executed by the SQLite backend.
The only argument passed to the callback is the statement (as
) that is being executed. The return value of the callback is ignored. Note that the backend does not only run statements passed to the
methods. Other sources include the
of the sqlite3 module and the execution of triggers defined in the current database.
Passing None as trace_callback will disable the trace callback.
Note
Exceptions raised in the trace callback are not propagated. As a development and debugging aid, use
to enable printing tracebacks from exceptions raised in the trace callback.
Added in version 3.3.
Changed in version 3.13: Passing trace_callback as a keyword argument is deprecated. The parameter will become positional-only in Python 3.15.
enable_load_extension(enabled, /)
Enable the SQLite engine to load SQLite extensions from shared libraries if enabled is True; else, disallow loading SQLite extensions. SQLite extensions can define new functions, aggregates or whole new virtual table implementations. One well-known extension is the fulltext-search extension distributed with SQLite.
Note
The sqlite3 module is not built with loadable extension support by default, because some platforms (notably macOS) have SQLite libraries which are compiled without this feature. To get loadable extension support, you must pass the
--enable-loadable-sqlite-extensions
option to configure.
Raises an
sqlite3.enable_load_extension with arguments connection, enabled.
Added in version 3.2.
Changed in version 3.10: Added the sqlite3.enable_load_extension auditing event.
con.enable_load_extension(True)# Load the fulltext search extensioncon.execute("select load_extension('./fts3.so')")# alternatively you can load the extension using an API call:# con.load_extension("./fts3.so")# disable extension loading againcon.enable_load_extension(False)# example from SQLite wikicon.execute("CREATE VIRTUAL TABLE recipe USING fts3(name, ingredients)")con.executescript(""" INSERT INTO recipe (name, ingredients) VALUES('broccoli stew', 'broccoli peppers cheese tomatoes'); INSERT INTO recipe (name, ingredients) VALUES('pumpkin stew', 'pumpkin onions garlic celery'); INSERT INTO recipe (name, ingredients) VALUES('broccoli pie', 'broccoli cheese onions flour'); INSERT INTO recipe (name, ingredients) VALUES('pumpkin pie', 'pumpkin sugar flour butter'); """)forrowincon.execute("SELECT rowid, name, ingredients FROM recipe WHERE name MATCH 'pie'"):print(row)load_extension(path, /, *, entrypoint=None)
Load an SQLite extension from a shared library. Enable extension loading with
before calling this method.
Parameters:path (
) – The path to the SQLite extension.
entrypoint (
| None) – Entry point name. If None (the default), SQLite will come up with an entry point name of its own; see the SQLite docs
for details.
Raises an
sqlite3.load_extension with arguments connection, path.
Added in version 3.2.
Changed in version 3.10: Added the sqlite3.load_extension auditing event.
Changed in version 3.12: Added the entrypoint parameter.
iterdump(*, filter=None)
Return an
to dump the database as SQL source code. Useful when saving an in-memory database for later restoration. Similar to the .dump command in the sqlite3 shell.
Parameters:filter (
| None) – An optional LIKE pattern for database objects to dump, e.g. prefix_%. If None (the default), all database objects will be included.
Example:
# Convert file example.db to SQL dump file dump.sqlcon=sqlite3.connect('example.db')withopen('dump.sql','w')asf:forlineincon.iterdump():f.write('%s\n'%line)con.close()Changed in version 3.13: Added the filter parameter.
backup(target, *, pages=-1, progress=None, name='main', sleep=0.250)
Create a backup of an SQLite database.
Works even if the database is being accessed by other clients or concurrently by the same connection.
Parameters:target (
) – The database connection to save the backup to.
pages (
) – The number of pages to copy at a time. If equal to or less than 0, the entire database is copied in a single step. Defaults to -1.
progress (
| None) – If set to a
, it is invoked with three integer arguments for every backup iteration: the status of the last iteration, the remaining number of pages still to be copied, and the total number of pages. Defaults to None.
name (
) – The name of the database to back up. Either "main" (the default) for the main database, "temp" for the temporary database, or the name of a custom database as attached using the ATTACHDATABASE SQL statement.
sleep (
) – The number of seconds to sleep between successive attempts to back up remaining pages.
Example 1, copy an existing database into another:
defprogress(status,remaining,total):print(f'Copied {total-remaining} of {total} pages...')src=sqlite3.connect('example.db')dst=sqlite3.connect('backup.db')withdst:src.backup(dst,pages=1,progress=progress)dst.close()src.close()Example 2, copy an existing database into a transient copy:
src=sqlite3.connect('example.db')dst=sqlite3.connect(':memory:')src.backup(dst)dst.close()src.close()Added in version 3.7.
getlimit(category, /)
Get a connection runtime limit.
Parameters:category (
) – The
to be queried.
Return type:
Raises:
– If category is not recognised by the underlying SQLite library.
Example, query the maximum length of an SQL statement for Connectioncon (the default is 1000000000):
>>> con.getlimit(sqlite3.SQLITE_LIMIT_SQL_LENGTH)1000000000Added in version 3.11.
setlimit(category, limit, /)
Set a connection runtime limit. Attempts to increase a limit above its hard upper bound are silently truncated to the hard upper bound. Regardless of whether or not the limit was changed, the prior value of the limit is returned.
Parameters:category (
) – The
to be set.
limit (
) – The value of the new limit. If negative, the current limit is unchanged.
Return type:
Raises:
– If category is not recognised by the underlying SQLite library.
Example, limit the number of attached databases to 1 for Connectioncon (the default limit is 10):
>>> con.setlimit(sqlite3.SQLITE_LIMIT_ATTACHED,1)10>>> con.getlimit(sqlite3.SQLITE_LIMIT_ATTACHED)1Added in version 3.11.
getconfig(op, /)
Query a boolean connection configuration option.
Parameters:op (
) – A
.
Return type:
Added in version 3.12.
setconfig(op, enable=True, /)
Set a boolean connection configuration option.
Parameters:op (
) – A
.
enable (
) – True if the configuration option should be enabled (default); False if it should be disabled.
Added in version 3.12.
serialize(*, name='main')
Serialize a database into a
object. For an ordinary on-disk database file, the serialization is just a copy of the disk file. For an in-memory database or a “temp” database, the serialization is the same sequence of bytes which would be written to disk if that database were backed up to disk.
Parameters:name (
) – The database name to be serialized. Defaults to "main".
Return type:
Note
This method is only available if the underlying SQLite library has the serialize API.
Added in version 3.11.
deserialize(data, /, *, name='main')
Deserialize a
database into a Connection. This method causes the database connection to disconnect from database name, and reopen name as an in-memory database based on the serialization contained in data.
Parameters:data (
) – A serialized database.
name (
) – The database name to deserialize into. Defaults to "main".
Raises:
– If the database connection is currently involved in a read transaction or a backup operation.
– If data does not contain a valid SQLite database.
– If
is larger than 2**63-1.
Note
This method is only available if the underlying SQLite library has the deserialize API.
Added in version 3.11.
autocommit
This attribute controls
-compliant transaction behaviour. autocommit has three allowed values:
False: Select
-compliant transaction behaviour, implying that sqlite3 ensures a transaction is always open. Use
and
to close transactions.
This is the recommended value of autocommit.
True: Use SQLite’s
.
and
have no effect in this mode.
: Pre-Python 3.12 (non-
-compliant) transaction control. See
for more details.
This is currently the default value of autocommit.
Changing autocommit to False will open a new transaction, and changing it to True will commit any pending transaction.
See
Transaction control via the autocommit attribute
for more details.
Note
The
attribute has no effect unless
is
.
Added in version 3.12.
in_transaction
This read-only attribute corresponds to the low-level SQLite
.
True if a transaction is active (there are uncommitted changes), False otherwise.
Added in version 3.2.
isolation_level
Controls the
legacy transaction handling mode
of sqlite3. If set to None, transactions are never implicitly opened. If set to one of "DEFERRED", "IMMEDIATE", or "EXCLUSIVE", corresponding to the underlying
,
implicit transaction management
is performed.
If not overridden by the isolation_level parameter of
, the default is "", which is an alias for "DEFERRED".
Note
Using
to control transaction handling is recommended over using isolation_level. isolation_level has no effect unless autocommit is set to
(the default).
row_factory
The initial
for
objects created from this connection. Assigning to this attribute does not affect the row_factory of existing cursors belonging to this connection, only new ones. Is None by default, meaning each row is returned as a
.
See
How to create and use row factories
for more details.
Changed in version 3.14.6: Deleting the row_factory attribute is no longer allowed.
text_factory
A
that accepts a
parameter and returns a text representation of it. The callable is invoked for SQLite values with the TEXT data type. By default, this attribute is set to
.
See
How to handle non-UTF-8 text encodings
for more details.
Changed in version 3.14.6: Deleting the text_factory attribute is no longer allowed.
total_changes
Return the total number of database rows that have been modified, inserted, or deleted since the database connection was opened.
Cursor objects
A Cursor object represents a
which is used to execute SQL statements, and manage the context of a fetch operation. Cursors are created using
, or by using any of the
.
Cursor objects are
, meaning that if you
a SELECT query, you can simply iterate over the cursor to fetch the resulting rows:
forrowincur.execute("SELECT t FROM data"):print(row)
classsqlite3.Cursor
A Cursor instance has the following attributes and methods.
execute(sql, parameters=(), /)
Execute a single SQL statement, optionally binding Python values using
.
Parameters:sql (
) – A single SQL statement.
parameters (
|
) – Python values to bind to placeholders in sql. A dict if named placeholders are used. A sequence if unnamed placeholders are used. See
How to use placeholders to bind values in SQL queries
.
Raises:
– When sql contains more than one SQL statement. When
are used and parameters is a sequence instead of a
.
If
is
,
is not None, sql is an INSERT, UPDATE, DELETE, or REPLACE statement, and there is no open transaction, a transaction is implicitly opened before executing sql.
Changed in version 3.14:
is emitted if
are used and parameters is a sequence instead of a
.
Use
to execute multiple SQL statements.
executemany(sql, parameters, /)
For every item in parameters, repeatedly execute the
DML SQL statement sql.
Uses the same implicit transaction handling as
.
Parameters:sql (
) – A single SQL DML statement.
parameters (
) – An iterable of parameters to bind with the placeholders in sql. See
How to use placeholders to bind values in SQL queries
.
Raises:
– When sql contains more than one SQL statement or is not a DML statement, When
are used and the items in parameters are sequences instead of
s.
Example:
rows=[("row1",),("row2",),]# cur is an sqlite3.Cursor objectcur.executemany("INSERT INTO data VALUES(?)",rows)Note
Any resulting rows are discarded, including DML statements with
.
Changed in version 3.14:
is emitted if
are used and the items in parameters are sequences instead of
s.
executescript(sql_script, /)
Execute the SQL statements in sql_script. If the
is
and there is a pending transaction, an implicit COMMIT statement is executed first. No other implicit transaction control is performed; any transaction control must be added to sql_script.
sql_script must be a
.
Example:
# cur is an sqlite3.Cursor objectcur.executescript(""" BEGIN; CREATE TABLE person(firstname, lastname, age); CREATE TABLE book(title, author, published); CREATE TABLE publisher(name, address); COMMIT;""")fetchone()
If
is None, return the next row query result set as a
. Else, pass it to the row factory and return its result. Return None if no more data is available.
fetchmany(size=cursor.arraysize)
Return the next set of rows of a query result as a
. Return an empty list if no more rows are available.
The number of rows to fetch per call is specified by the size parameter. If size is not given,
determines the number of rows to be fetched. If fewer than size rows are available, as many rows as are available are returned.
Note there are performance considerations involved with the size parameter. For optimal performance, it is usually best to use the arraysize attribute. If the size parameter is used, then it is best for it to retain the same value from one fetchmany() call to the next.
Changed in version 3.14.1: Negative size values are rejected by raising
.
fetchall()
Return all (remaining) rows of a query result as a
. Return an empty list if no rows are available. Note that the
attribute can affect the performance of this operation.
close()
Close the cursor now (rather than whenever __del__ is called).
The cursor will be unusable from this point forward; a
exception will be raised if any operation is attempted with the cursor.
setinputsizes(sizes, /)
Required by the DB-API. Does nothing in sqlite3.
setoutputsize(size, column=None, /)
Required by the DB-API. Does nothing in sqlite3.
arraysize
Read/write attribute that controls the number of rows returned by
. The default value is 1 which means a single row would be fetched per call.
Changed in version 3.14.1: Negative values are rejected by raising
.
connection
Read-only attribute that provides the SQLite database
belonging to the cursor. A Cursor object created by calling
will have a
attribute that refers to con:
>>> con=sqlite3.connect(":memory:")>>> cur=con.cursor()>>> cur.connection==conTrue>>> con.close()description
Read-only attribute that provides the column names of the last query. To remain compatible with the Python DB API, it returns a 7-tuple for each column where the last six items of each tuple are None.
It is set for SELECT statements without any matching rows as well.
lastrowid
Read-only attribute that provides the row id of the last inserted row. It is only updated after successful INSERT or REPLACE statements using the
method. For other statements, after
or
, or if the insertion failed, the value of lastrowid is left unchanged. The initial value of lastrowid is None.
Note
Inserts into WITHOUTROWID tables are not recorded.
Changed in version 3.6: Added support for the REPLACE statement.
rowcount
Read-only attribute that provides the number of modified rows for INSERT, UPDATE, DELETE, and REPLACE statements; is -1 for other statements, including CTE queries. It is only updated by the
and
methods, after the statement has run to completion. This means that any resulting rows must be fetched in order for rowcount to be updated.
row_factory
Control how a row fetched from this Cursor is represented. If None, a row is represented as a
. Can be set to the included
; or a
that accepts two arguments, a Cursor object and the tuple of row values, and returns a custom object representing an SQLite row.
Defaults to what
was set to when the Cursor was created. Assigning to this attribute does not affect Connection.row_factory of the parent connection.
See
How to create and use row factories
for more details.
Changed in version 3.14.6: Deleting the row_factory attribute is no longer allowed.
Row objects
classsqlite3.Row
A Row instance serves as a highly optimized
for
objects. It supports iteration, equality testing,
, and
access by column name and index.
Two Row objects compare equal if they have identical column names and values.
See
How to create and use row factories
for more details.
keys()
Return a
of column names as
. Immediately after a query, it is the first member of each tuple in
.
Changed in version 3.5: Added support of slicing.
Blob objects
classsqlite3.Blob
Added in version 3.11.
A Blob instance is a
that can read and write data in an SQLite BLOB. Call
to get the size (number of bytes) of the blob. Use indices and
for direct access to the blob data.
Use the Blob as a
to ensure that the blob handle is closed after use.
con=sqlite3.connect(":memory:")con.execute("CREATE TABLE test(blob_col blob)")con.execute("INSERT INTO test(blob_col) VALUES(zeroblob(13))")# Write to our blob, using two write operations:withcon.blobopen("test","blob_col",1)asblob:blob.write(b"hello, ")blob.write(b"world.")# Modify the first and last bytes of our blobblob[0]=ord("H")blob[-1]=ord("!")# Read the contents of our blobwithcon.blobopen("test","blob_col",1)asblob:greeting=blob.read()print(greeting)# outputs "b'Hello, world!'"con.close()close()
Close the blob.
The blob will be unusable from this point onward. An
(or subclass) exception will be raised if any further operation is attempted with the blob.
read(length=-1, /)
Read length bytes of data from the blob at the current offset position. If the end of the blob is reached, the data up to EOF will be returned. When length is not specified, or is negative, read() will read until the end of the blob.
write(data, /)
Write data to the blob at the current offset. This function cannot change the blob length. Writing beyond the end of the blob will raise
.
tell()
Return the current access position of the blob.
seek(offset, origin=os.SEEK_SET, /)
Set the current access position of the blob to offset. The origin argument defaults to
(absolute blob positioning). Other values for origin are
(seek relative to the current position) and
(seek relative to the blob’s end).
PrepareProtocol objects
classsqlite3.PrepareProtocol
The PrepareProtocol type’s single purpose is to act as a
style adaption protocol for objects that can
to
.
Exceptions
The exception hierarchy is defined by the DB-API 2.0 (
).
exceptionsqlite3.Warning
This exception is not currently raised by the sqlite3 module, but may be raised by applications using sqlite3, for example if a user-defined function truncates data while inserting. Warning is a subclass of
.
exceptionsqlite3.Error
The base class of the other exceptions in this module. Use this to catch all errors with one single
statement. Error is a subclass of
.
If the exception originated from within the SQLite library, the following two attributes are added to the exception:
sqlite_errorcode
The numeric error code from the
Added in version 3.11.
sqlite_errorname
The symbolic name of the numeric error code from the
Added in version 3.11.
exceptionsqlite3.InterfaceError
Exception raised for misuse of the low-level SQLite C API. In other words, if this exception is raised, it probably indicates a bug in the sqlite3 module. InterfaceError is a subclass of
.
exceptionsqlite3.DatabaseError
Exception raised for errors that are related to the database. This serves as the base exception for several types of database errors. It is only raised implicitly through the specialised subclasses. DatabaseError is a subclass of
.
exceptionsqlite3.DataError
Exception raised for errors caused by problems with the processed data, like numeric values out of range, and strings which are too long. DataError is a subclass of
.
exceptionsqlite3.OperationalError
Exception raised for errors that are related to the database’s operation, and not necessarily under the control of the programmer. For example, the database path is not found, or a transaction could not be processed. OperationalError is a subclass of
.
exceptionsqlite3.IntegrityError
Exception raised when the relational integrity of the database is affected, e.g. a foreign key check fails. It is a subclass of
.
exceptionsqlite3.InternalError
Exception raised when SQLite encounters an internal error. If this is raised, it may indicate that there is a problem with the runtime SQLite library. InternalError is a subclass of
.
exceptionsqlite3.ProgrammingError
Exception raised for sqlite3 API programming errors, for example supplying the wrong number of bindings to a query, or trying to operate on a closed
. ProgrammingError is a subclass of
.
exceptionsqlite3.NotSupportedError
Exception raised in case a method or database API is not supported by the underlying SQLite library. For example, setting deterministic to True in
, if the underlying SQLite library does not support deterministic functions. NotSupportedError is a subclass of
.
SQLite and Python types
SQLite natively supports the following types: NULL, INTEGER, REAL, TEXT, BLOB.
The following Python types can thus be sent to SQLite without any problem:
Python type
SQLite type
None
NULL
INTEGER
REAL
TEXT
BLOB
This is how SQLite types are converted to Python types by default:
SQLite type
Python type
NULL
None
INTEGER
REAL
TEXT
depends on
,
by default
BLOB
The type system of the sqlite3 module is extensible in two ways: you can store additional Python types in an SQLite database via
, and you can let the sqlite3 module convert SQLite types to Python types via
.
Default adapters and converters (deprecated)
Note
The default adapters and converters are deprecated as of Python 3.12. Instead, use the
and tailor them to your needs.
The deprecated default adapters and converters consist of:
An adapter for
objects to
in
format.
An adapter for
objects to strings in ISO 8601 format.
A converter for
“date” types to
objects.
A converter for declared “timestamp” types to
objects. Fractional parts will be truncated to 6 digits (microsecond precision).
Note
The default “timestamp” converter ignores UTC offsets in the database and always returns a naive
object. To preserve UTC offsets in timestamps, either leave converters disabled, or register an offset-aware converter with
.
Deprecated since version 3.12.
Command-line interface
The sqlite3 module can be invoked as a script, using the interpreter’s
switch, in order to provide a simple SQLite shell. The argument signature is as follows:
python-msqlite3[-h][-v][filename][sql]Type .quit or CTRL-D to exit the shell.
-h,--help
Print CLI help.
-v,--version
Print underlying SQLite library version.
Added in version 3.12.
How-to guides
How to use placeholders to bind values in SQL queries
SQL operations usually need to use values from Python variables. However, beware of using Python’s string operations to assemble queries, as they are vulnerable to
. For example, an attacker can simply close the single quote and inject ORTRUE to select all rows:
>>> # Never do this -- insecure!>>> symbol=input()' OR TRUE; -->>> sql="SELECT * FROM stocks WHERE symbol = '%s'"%symbol>>> print(sql)SELECT * FROM stocks WHERE symbol = '' OR TRUE; --'>>> cur.execute(sql)Instead, use the DB-API’s parameter substitution. To insert a variable into a query string, use a placeholder in the string, and substitute the actual values into the query by providing them as a
of values to the second argument of the cursor’s
method.
An SQL statement may use one of two kinds of placeholders: question marks (qmark style) or named placeholders (named style). For the qmark style, parameters must be a
whose length must match the number of placeholders, or a
is raised. For the named style, parameters must be an instance of a
(or a subclass), which must contain keys for all named parameters; any extra items are ignored. Here’s an example of both styles:
con=sqlite3.connect(":memory:")cur=con.execute("CREATE TABLE lang(name, first_appeared)")# This is the named style used with executemany():data=({"name":"C","year":1972},{"name":"Fortran","year":1957},{"name":"Python","year":1991},{"name":"Go","year":2009},)cur.executemany("INSERT INTO lang VALUES(:name, :year)",data)# This is the qmark style used in a SELECT query:params=(1972,)cur.execute("SELECT * FROM lang WHERE first_appeared = ?",params)print(cur.fetchall())con.close()Note
numeric placeholders are not supported. If used, they will be interpreted as named placeholders.
How to adapt custom Python types to SQLite values
SQLite supports only a limited set of data types natively. To store custom Python types in SQLite databases, adapt them to one of the
Python types SQLite natively understands
.
There are two ways to adapt Python objects to SQLite types: letting your object adapt itself, or using an adapter callable. The latter will take precedence above the former. For a library that exports a custom type, it may make sense to enable that type to adapt itself. As an application developer, it may make more sense to take direct control by registering custom adapter functions.
How to write adaptable objects
Suppose we have a Point class that represents a pair of coordinates, x and y, in a Cartesian coordinate system. The coordinate pair will be stored as a text string in the database, using a semicolon to separate the coordinates. This can be implemented by adding a __conform__(self,protocol) method which returns the adapted value. The object passed to protocol will be of type
.
classPoint:def__init__(self,x,y):self.x,self.y=x,ydef__conform__(self,protocol):ifprotocolissqlite3.PrepareProtocol:returnf"{self.x};{self.y}"con=sqlite3.connect(":memory:")cur=con.cursor()cur.execute("SELECT ?",(Point(4.0,-3.2),))print(cur.fetchone()[0])con.close()How to register adapter callables
The other possibility is to create a function that converts the Python object to an SQLite-compatible type. This function can then be registered using
.
classPoint:def__init__(self,x,y):self.x,self.y=x,ydefadapt_point(point):returnf"{point.x};{point.y}"sqlite3.register_adapter(Point,adapt_point)con=sqlite3.connect(":memory:")cur=con.cursor()cur.execute("SELECT ?",(Point(1.0,2.5),))print(cur.fetchone()[0])con.close()How to convert SQLite values to custom Python types
Writing an adapter lets you convert from custom Python types to SQLite values. To be able to convert from SQLite values to custom Python types, we use converters.
Let’s go back to the Point class. We stored the x and y coordinates separated via semicolons as strings in SQLite.
First, we’ll define a converter function that accepts the string as a parameter and constructs a Point object from it.
Note
Converter functions are always passed a
object, no matter the underlying SQLite data type.
defconvert_point(s):x,y=map(float,s.split(b";"))returnPoint(x,y)We now need to tell sqlite3 when it should convert a given SQLite value. This is done when connecting to a database, using the detect_types parameter of
. There are three options:
Implicit: set detect_types to
Explicit: set detect_types to
Both: set detect_types to sqlite3.PARSE_DECLTYPES|sqlite3.PARSE_COLNAMES. Column names take precedence over declared types.
The following example illustrates the implicit and explicit approaches:
classPoint:def__init__(self,x,y):self.x,self.y=x,ydef__repr__(self):returnf"Point({self.x}, {self.y})"defadapt_point(point):returnf"{point.x};{point.y}"defconvert_point(s):x,y=list(map(float,s.split(b";")))returnPoint(x,y)# Register the adapter and convertersqlite3.register_adapter(Point,adapt_point)sqlite3.register_converter("point",convert_point)# 1) Parse using declared typesp=Point(4.0,-3.2)con=sqlite3.connect(":memory:",detect_types=sqlite3.PARSE_DECLTYPES)cur=con.execute("CREATE TABLE test(p point)")cur.execute("INSERT INTO test(p) VALUES(?)",(p,))cur.execute("SELECT p FROM test")print("with declared types:",cur.fetchone()[0])cur.close()con.close()# 2) Parse using column namescon=sqlite3.connect(":memory:",detect_types=sqlite3.PARSE_COLNAMES)cur=con.execute("CREATE TABLE test(p)")cur.execute("INSERT INTO test(p) VALUES(?)",(p,))cur.execute('SELECT p AS "p [point]" FROM test')print("with column names:",cur.fetchone()[0])cur.close()con.close()Adapter and converter recipes
This section shows recipes for common adapters and converters.
importdatetimeasdtimportsqlite3defadapt_date_iso(val):"""Adapt datetime.date to ISO 8601 date."""returnval.isoformat()defadapt_datetime_iso(val):"""Adapt datetime.datetime to timezone-naive ISO 8601 date."""returnval.replace(tzinfo=None).isoformat()defadapt_datetime_epoch(val):"""Adapt datetime.datetime to Unix timestamp."""returnint(val.timestamp())sqlite3.register_adapter(dt.date,adapt_date_iso)sqlite3.register_adapter(dt.datetime,adapt_datetime_iso)sqlite3.register_adapter(dt.datetime,adapt_datetime_epoch)defconvert_date(val):"""Convert ISO 8601 date to datetime.date object."""returndt.date.fromisoformat(val.decode())defconvert_datetime(val):"""Convert ISO 8601 datetime to datetime.datetime object."""returndt.datetime.fromisoformat(val.decode())defconvert_timestamp(val):"""Convert Unix epoch timestamp to datetime.datetime object."""returndt.datetime.fromtimestamp(int(val))sqlite3.register_converter("date",convert_date)sqlite3.register_converter("datetime",convert_datetime)sqlite3.register_converter("timestamp",convert_timestamp)How to use connection shortcut methods
Using the
,
, and
methods of the
class, your code can be written more concisely because you don’t have to create the (often superfluous)
objects explicitly. Instead, the Cursor objects are created implicitly and these shortcut methods return the cursor objects. This way, you can execute a SELECT statement and iterate over it directly using only a single call on the Connection object.
# Create and fill the table.con=sqlite3.connect(":memory:")con.execute("CREATE TABLE lang(name, first_appeared)")data=[("C++",1985),("Objective-C",1984),]con.executemany("INSERT INTO lang(name, first_appeared) VALUES(?, ?)",data)# Print the table contentsforrowincon.execute("SELECT name, first_appeared FROM lang"):print(row)print("I just deleted",con.execute("DELETE FROM lang").rowcount,"rows")# close() is not a shortcut method and it's not called automatically;# the connection object should be closed manuallycon.close()How to use the connection context manager
A
object can be used as a context manager that automatically commits or rolls back open transactions when leaving the body of the context manager. If the body of the
statement finishes without exceptions, the transaction is committed. If this commit fails, or if the body of the with statement raises an uncaught exception, the transaction is rolled back. If
is False, a new transaction is implicitly opened after committing or rolling back.
If there is no open transaction upon leaving the body of the with statement, or if
is True, the context manager does nothing.
Note
The context manager neither implicitly opens a new transaction nor closes the connection. If you need a closing context manager, consider using
.
con=sqlite3.connect(":memory:")con.execute("CREATE TABLE lang(id INTEGER PRIMARY KEY, name VARCHAR UNIQUE)")# Successful, con.commit() is called automatically afterwardswithcon:con.execute("INSERT INTO lang(name) VALUES(?)",("Python",))# con.rollback() is called after the with block finishes with an exception,# the exception is still raised and must be caughttry:withcon:con.execute("INSERT INTO lang(name) VALUES(?)",("Python",))exceptsqlite3.IntegrityError:print("couldn't add Python twice")# Connection object used as context manager only commits or rollbacks transactions,# so the connection object should be closed manuallycon.close()How to work with SQLite URIs
Some useful URI tricks include:
Open a database in read-only mode:
>>> con=sqlite3.connect("file:tutorial.db?mode=ro",uri=True)>>> con.execute("CREATE TABLE readonly(data)")Traceback (most recent call last):OperationalError: attempt to write a readonly database>>> con.close()Do not implicitly create a new database file if it does not already exist; will raise
if unable to create a new file:
>>> con=sqlite3.connect("file:nosuchdb.db?mode=rw",uri=True)Traceback (most recent call last):OperationalError: unable to open database fileCreate a shared named in-memory database:
db="file:mem1?mode=memory&cache=shared"con1=sqlite3.connect(db,uri=True)con2=sqlite3.connect(db,uri=True)withcon1:con1.execute("CREATE TABLE shared(data)")con1.execute("INSERT INTO shared VALUES(28)")res=con2.execute("SELECT data FROM shared")assertres.fetchone()==(28,)con1.close()con2.close()More information about this feature, including a list of parameters, can be found in the
.
How to create and use row factories
By default, sqlite3 represents each row as a
. If a tuple does not suit your needs, you can use the
class or a custom
.
While row_factory exists as an attribute both on the
and the
, it is recommended to set
, so all cursors created from the connection will use the same row factory.
Row provides indexed and case-insensitive named access to columns, with minimal memory overhead and performance impact over a tuple. To use Row as a row factory, assign it to the row_factory attribute:
>>> con=sqlite3.connect(":memory:")>>> con.row_factory=sqlite3.RowQueries now return Row objects:
>>> res=con.execute("SELECT 'Earth' AS name, 6378 AS radius")>>> row=res.fetchone()>>> row.keys()['name', 'radius']>>> row[0]# Access by index.'Earth'>>> row["name"]# Access by name.'Earth'>>> row["RADIUS"]# Column names are case-insensitive.6378>>> con.close()Note
The FROM clause can be omitted in the SELECT statement, as in the above example. In such cases, SQLite returns a single row with columns defined by expressions, e.g. literals, with the given aliases exprASalias.
You can create a custom
that returns each row as a
, with column names mapped to values:
defdict_factory(cursor,row):fields=[column[0]forcolumnincursor.description]return{key:valueforkey,valueinzip(fields,row)}Using it, queries now return a dict instead of a tuple:
>>> con=sqlite3.connect(":memory:")>>> con.row_factory=dict_factory>>> forrowincon.execute("SELECT 1 AS a, 2 AS b"):... print(row){'a': 1, 'b': 2}>>> con.close()The following row factory returns a
:
fromcollectionsimportnamedtupledefnamedtuple_factory(cursor,row):fields=[column[0]forcolumnincursor.description]cls=namedtuple("Row",fields)returncls._make(row)namedtuple_factory() can be used as follows:
>>> con=sqlite3.connect(":memory:")>>> con.row_factory=namedtuple_factory>>> cur=con.execute("SELECT 1 AS a, 2 AS b")>>> row=cur.fetchone()>>> rowRow(a=1, b=2)>>> row[0]# Indexed access.1>>> row.b# Attribute access.2>>> con.close()With some adjustments, the above recipe can be adapted to use a
, or any other custom class, instead of a
.
How to handle non-UTF-8 text encodings
By default, sqlite3 uses
to adapt SQLite values with the TEXT data type. This works well for UTF-8 encoded text, but it might fail for other encodings and invalid UTF-8. You can use a custom
to handle such cases.
Because of SQLite’s
, it is not uncommon to encounter table columns with the TEXT data type containing non-UTF-8 encodings, or even arbitrary data. To demonstrate, let’s assume we have a database with ISO-8859-2 (Latin-2) encoded text, for example a table of Czech-English dictionary entries. Assuming we now have a
instance con connected to this database, we can decode the Latin-2 encoded text using this
:
con.text_factory=lambdadata:str(data,encoding="latin2")For invalid UTF-8 or arbitrary data in stored in TEXT table columns, you can use the following technique, borrowed from the
:
con.text_factory=lambdadata:str(data,errors="surrogateescape")Note
The sqlite3 module API does not support strings containing surrogates.
Explanation
Transaction control
sqlite3 offers multiple methods of controlling whether, when and how database transactions are opened and closed.
Transaction control via the autocommit attribute
is recommended, while
Transaction control via the isolation_level attribute
retains the pre-Python 3.12 behaviour.
Transaction control via the autocommit attribute
The recommended way of controlling transaction behaviour is through the
attribute, which should preferably be set using the autocommit parameter of
.
It is suggested to set autocommit to False, which implies
-compliant transaction control. This means:
sqlite3 ensures that a transaction is always open, so
,
, and
will implicitly open a new transaction (immediately after closing the pending one, for the latter two). sqlite3 uses BEGINDEFERRED statements when opening transactions.
Transactions should be committed explicitly using commit().
Transactions should be rolled back explicitly using rollback().
An implicit rollback is performed if the database is
-ed with pending changes.
Set autocommit to True to enable SQLite’s
. In this mode,
and
have no effect. Note that SQLite’s autocommit mode is distinct from the
-compliant
attribute; use
to query the low-level SQLite autocommit mode.
Set autocommit to
to leave transaction control behaviour to the
attribute. See
Transaction control via the isolation_level attribute
for more information.
Transaction control via the isolation_level attribute
Note
The recommended way of controlling transactions is via the
attribute. See
Transaction control via the autocommit attribute
.
If
is set to
(the default), transaction behaviour is controlled using the
attribute. Otherwise, isolation_level has no effect.
If the connection attribute
is not None, new transactions are implicitly opened before
and
executes INSERT, UPDATE, DELETE, or REPLACE statements; for other statements, no implicit transaction handling is performed. Use the
and
methods to respectively commit and roll back pending transactions. You can choose the underlying
— that is, whether and what type of BEGIN statements sqlite3 implicitly executes – via the isolation_level attribute.
If
is set to None, no transactions are implicitly opened at all. This leaves the underlying SQLite library in
, but also allows the user to perform their own transaction handling using explicit SQL statements. The underlying SQLite library autocommit mode can be queried using the
attribute.
The
method implicitly commits any pending transaction before execution of the given SQL script, regardless of the value of
.
Changed in version 3.6: sqlite3 used to implicitly commit an open transaction before DDL statements. This is no longer the case.
Changed in version 3.12: The recommended way of controlling transactions is now via the
attribute.