QSqlDriver¶

PyQt5.QtSql.QSqlDriver: Inherits from QObject.

Description¶

The QSqlDriver class is an abstract base class for accessing specific SQL databases.

This class should not be used directly. Use QSqlDatabase instead.

If you want to create your own SQL drivers, you can subclass this class and reimplement its pure virtual functions and those virtual functions that you need. See How to Write Your Own Database Driver for more information.

See also

QSqlDatabase, QSqlResult.

Enums¶

DbmsType

This enum contains DBMS types.

Member	Value	Description
DB2	TODO	TODO
Interbase	TODO	TODO
MSSqlServer	TODO	TODO
MySqlServer	TODO	TODO
Oracle	TODO	TODO
PostgreSQL	TODO	TODO
SQLite	TODO	TODO
Sybase	TODO	TODO
UnknownDbms	TODO	TODO

DriverFeature

This enum contains a list of features a driver might support. Use hasFeature() to query whether a feature is supported or not.

More information about supported features can be found in the Qt SQL driver documentation.

See also

hasFeature().

Member	Value	Description
BatchOperations	8	Whether the driver supports batched operations, see execBatch()
BLOB	2	Whether the driver supports Binary Large Object fields.
EventNotifications	11	Whether the driver supports database event notifications.
FinishQuery	12	Whether the driver can do any low-level resource cleanup when finish() is called.
LastInsertId	7	Whether the driver supports returning the Id of the last touched row.
LowPrecisionNumbers	10	Whether the driver allows fetching numerical values with low precision.
MultipleResultSets	13	Whether the driver can access multiple result sets returned from batched statements or stored procedures.
NamedPlaceholders	5	Whether the driver supports the use of named placeholders.
PositionalPlaceholders	6	Whether the driver supports the use of positional placeholders.
PreparedQueries	4	Whether the driver supports prepared query execution.
QuerySize	1	Whether the database is capable of reporting the size of a query. Note that some databases do not support returning the size (i.e. number of rows returned) of a query, in which case size() will return -1.
SimpleLocking	9	Whether the driver disallows a write lock on a table while other queries have a read lock on it.
Transactions	0	Whether the driver supports SQL transactions.
Unicode	3	Whether the driver supports Unicode strings if the database server does.

IdentifierType

This enum contains a list of SQL identifier types.

Member	Value	Description
FieldName	0	A SQL field name
TableName	1	A SQL table name

NotificationSource

This enum contains a list of SQL notification sources.

Member	Value	Description
OtherSource	2	The notification source is another connection
SelfSource	1	The notification source is this connection
UnknownSource	0	The notification source is unknown

StatementType

This enum contains a list of SQL statement (or clause) types the driver can create.

See also

sqlStatement().

Member	Value	Description
DeleteStatement	4	An SQL `DELETE` statement (e.g., `DELETE FROM t`).
InsertStatement	3	An SQL `INSERT` statement (e.g., `INSERT INTO t (f) values (1)`).
SelectStatement	1	An SQL `SELECT` statement (e.g., `SELECT f FROM t`).
UpdateStatement	2	An SQL `UPDATE` statement (e.g., `UPDATE TABLE t set f = 1`).
WhereStatement	0	An SQL `WHERE` statement (e.g., `WHERE f = 5`).

Methods¶

__init__(parent: QObject = None): Constructs a new driver with the given parent.

beginTransaction() → bool: This function is called to begin a transaction. If successful, return true, otherwise return false. The default implementation does nothing and returns false.

See also

commitTransaction(), rollbackTransaction().

close(): TODO

commitTransaction() → bool: This function is called to commit a transaction. If successful, return true, otherwise return false. The default implementation does nothing and returns false.

See also

beginTransaction(), rollbackTransaction().

createResult() → QSqlResult: TODO

dbmsType() → DbmsType: Returns the current DBMS type for the database connection.

escapeIdentifier(str, IdentifierType) → str

Returns the identifier escaped according to the database rules. identifier can either be a table name or field name, dependent on type.

The default implementation does nothing.

See also

isIdentifierEscaped().

formatValue(QSqlField, trimStrings: bool = False) → str

Returns a string representation of the field value for the database. This is used, for example, when constructing INSERT and UPDATE statements.

The default implementation returns the value formatted as a string according to the following rules:

If field is character data, the value is returned enclosed in single quotation marks, which is appropriate for many SQL databases. Any embedded single-quote characters are escaped (replaced with two single-quote characters). If trimStrings is true (the default is false), all trailing whitespace is trimmed from the field.
If field is date/time data, the value is formatted in ISO format and enclosed in single quotation marks. If the date/time data is invalid, “NULL” is returned.
If field is QByteArray data, and the driver can edit binary fields, the value is formatted as a hexadecimal string.
For any other field type, toString() is called on its value and the result of this is returned.

See also

QVariant::toString().

handle() → Any

Returns the low-level database handle wrapped in a QVariant or an invalid variant if there is no handle.

Warning: Use this with uttermost care and only if you know what you’re doing.

Warning: The handle returned here can become a stale pointer if the connection is modified (for example, if you close the connection).

Warning: The handle can be NULL if the connection is not open yet.

The handle returned here is database-dependent, you should query the type name of the variant before accessing it.

This example retrieves the handle for a connection to sqlite:

# QSqlDatabase db = ...;
# QVariant v = db.driver()->handle();
# if (v.isValid() && qstrcmp(v.typeName(), "sqlite3*") == 0) {
#     // v.data() returns a pointer to the handle
#     sqlite3 *handle = *static_cast<sqlite3 **>(v.data());
#     if (handle) {
#         ...
#     }
# }

This snippet returns the handle for or MySQL:

# if (qstrcmp(v.typeName(), "PGconn*") == 0) {
#     PGconn *handle = *static_cast<PGconn **>(v.data());
#     if (handle) ...
# }

# if (qstrcmp(v.typeName(), "MYSQL*") == 0) {
#     MYSQL *handle = *static_cast<MYSQL **>(v.data());
#     if (handle) ...
# }

See also

handle().

hasFeature(DriverFeature) → bool: TODO

isIdentifierEscaped(str, IdentifierType) → bool

Returns whether identifier is escaped according to the database rules. identifier can either be a table name or field name, dependent on type.

Reimplement this function if you want to provide your own implementation in your QSqlDriver subclass,

See also

stripDelimiters(), escapeIdentifier().

isOpen() → bool: Returns true if the database connection is open; otherwise returns false.

isOpenError() → bool: Returns true if the there was an error opening the database connection; otherwise returns false.

lastError() → QSqlError: Returns a QSqlError object which contains information about the last error that occurred on the database.

See also

setLastError().

numericalPrecisionPolicy() → NumericalPrecisionPolicy: Returns the current default precision policy for the database connection.

See also

setNumericalPrecisionPolicy(), numericalPrecisionPolicy(), setNumericalPrecisionPolicy(), NumericalPrecisionPolicy.

open(str, user: str = '', password: str = '', host: str = '', port: int = -1, options: str = '') → bool: TODO

primaryIndex(str) → QSqlIndex: Returns the primary index for table tableName. Returns an empty QSqlIndex if the table doesn’t have a primary index. The default implementation returns an empty index.

record(str) → QSqlRecord: Returns a QSqlRecord populated with the names of the fields in table tableName. If no such table exists, an empty record is returned. The default implementation returns an empty record.

rollbackTransaction() → bool: This function is called to rollback a transaction. If successful, return true, otherwise return false. The default implementation does nothing and returns false.

See also

beginTransaction(), commitTransaction().

setLastError(QSqlError): This function is used to set the value of the last error, error, that occurred on the database.

See also

lastError().

setNumericalPrecisionPolicy(NumericalPrecisionPolicy): TODO

setOpen(bool): This function sets the open state of the database to open. Derived classes can use this function to report the status of open().

See also

open(), setOpenError().

setOpenError(bool): This function sets the open error state of the database to error. Derived classes can use this function to report the status of open(). Note that if error is true the open state of the database is set to closed (i.e., isOpen() returns false).

See also

isOpenError(), open(), setOpen().

sqlStatement(StatementType, str, QSqlRecord, bool) → str

Returns a SQL statement of type type for the table tableName with the values from rec. If preparedStatement is true, the string will contain placeholders instead of values.

The generated flag in each field of rec determines whether the field is included in the generated statement.

This method can be used to manipulate tables without having to worry about database-dependent SQL dialects. For non-prepared statements, the values will be properly escaped.

In the WHERE statement, each non-null field of rec specifies a filter condition of equality to the field value, or if prepared, a placeholder. However, prepared or not, a null field specifies the condition IS NULL and never introduces a placeholder. The application must not attempt to bind data for the null field during execution. The field must be set to some non-null value if a placeholder is desired. Furthermore, since non-null fields specify equality conditions and SQL NULL is not equal to anything, even itself, it is generally not useful to bind a null to a placeholder.

stripDelimiters(str, IdentifierType) → str

Returns the identifier with the leading and trailing delimiters removed, identifier can either be a table name or field name, dependent on type. If identifier does not have leading and trailing delimiter characters, identifier is returned without modification.

Reimplement this function if you want to provide your own implementation in your QSqlDriver subclass,

See also

isIdentifierEscaped().

subscribedToNotifications() → List[str]

Returns a list of the names of the event notifications that are currently subscribed to.

Reimplement this function if you want to provide event notification support in your own QSqlDriver subclass,

subscribeToNotification(str) → bool

This function is called to subscribe to event notifications from the database. name identifies the event notification.

If successful, return true, otherwise return false.

The database must be open when this function is called. When the database is closed by calling close() all subscribed event notifications are automatically unsubscribed. Note that calling open() on an already open database may implicitly cause close() to be called, which will cause the driver to unsubscribe from all event notifications.

When an event notification identified by name is posted by the database the notification signal is emitted.

Reimplement this function if you want to provide event notification support in your own QSqlDriver subclass,

tables(TableType) → List[str]: TODO

unsubscribeFromNotification(str) → bool

This function is called to unsubscribe from event notifications from the database. name identifies the event notification.

If successful, return true, otherwise return false.

The database must be open when this function is called. All subscribed event notifications are automatically unsubscribed from when the close() function is called.

After calling this function the notification signal will no longer be emitted when an event notification identified by name is posted by the database.

Reimplement this function if you want to provide event notification support in your own QSqlDriver subclass,

Signals¶

notification(str): TODO

notification(str, NotificationSource, Any): TODO