QSqlDriver#
The QSqlDriver
class is an abstract base class for accessing specific SQL databases. More…
Synopsis#
Functions#
def
dbmsType
()def
isOpenError
()def
lastError
()def
numericalPrecisionPolicy
()def
setNumericalPrecisionPolicy
(precisionPolicy)
Virtual functions#
def
beginTransaction
()def
cancelQuery
()def
close
()def
commitTransaction
()def
createResult
()def
escapeIdentifier
(identifier, type)def
formatValue
(field[, trimStrings=false])def
hasFeature
(f)def
isIdentifierEscaped
(identifier, type)def
isOpen
()def
maximumIdentifierLength
(type)def
open
(db[, user=””[, password=””[, host=””[, port=-1[, connOpts=””]]]]])def
primaryIndex
(tableName)def
record
(tableName)def
rollbackTransaction
()def
setLastError
(e)def
setOpen
(o)def
setOpenError
(e)def
sqlStatement
(type, tableName, rec, preparedStatement)def
stripDelimiters
(identifier, type)def
subscribeToNotification
(name)def
subscribedToNotifications
()def
tables
(tableType)def
unsubscribeFromNotification
(name)
Signals#
def
notification
(name, source, payload)
Note
This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE
Detailed Description#
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
- class PySide6.QtSql.QSqlDriver([parent=None])#
- Parameters:
parent –
PySide6.QtCore.QObject
Constructs a new driver with the given parent
.
- PySide6.QtSql.QSqlDriver.DriverFeature#
This enum contains a list of features a driver might support. Use hasFeature()
to query whether a feature is supported or not.
Constant
Description
QSqlDriver.Transactions
Whether the driver supports SQL transactions.
QSqlDriver.QuerySize
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.QSqlDriver.BLOB
Whether the driver supports Binary Large Object fields.
QSqlDriver.Unicode
Whether the driver supports Unicode strings if the database server does.
QSqlDriver.PreparedQueries
Whether the driver supports prepared query execution.
QSqlDriver.NamedPlaceholders
Whether the driver supports the use of named placeholders.
QSqlDriver.PositionalPlaceholders
Whether the driver supports the use of positional placeholders.
QSqlDriver.LastInsertId
Whether the driver supports returning the Id of the last touched row.
QSqlDriver.BatchOperations
Whether the driver supports batched operations, see
execBatch()
QSqlDriver.SimpleLocking
Whether the driver disallows a write lock on a table while other queries have a read lock on it.
QSqlDriver.LowPrecisionNumbers
Whether the driver allows fetching numerical values with low precision.
QSqlDriver.EventNotifications
Whether the driver supports database event notifications.
QSqlDriver.FinishQuery
Whether the driver can do any low-level resource cleanup when
finish()
is called.QSqlDriver.MultipleResultSets
Whether the driver can access multiple result sets returned from batched statements or stored procedures.
QSqlDriver.CancelQuery
Whether the driver allows cancelling a running query.
More information about supported features can be found in the Qt SQL driver documentation.
See also
- PySide6.QtSql.QSqlDriver.StatementType#
This enum contains a list of SQL statement (or clause) types the driver can create.
Constant
Description
QSqlDriver.WhereStatement
An SQL
WHERE
statement (e.g.,WHERE f = 5
).QSqlDriver.SelectStatement
An SQL
SELECT
statement (e.g.,SELECT f FROM t
).QSqlDriver.UpdateStatement
An SQL
UPDATE
statement (e.g.,UPDATE TABLE t set f = 1
).QSqlDriver.InsertStatement
An SQL
INSERT
statement (e.g.,INSERT INTO t (f) values (1)
).QSqlDriver.DeleteStatement
An SQL
DELETE
statement (e.g.,DELETE FROM t
).See also
- PySide6.QtSql.QSqlDriver.IdentifierType#
This enum contains a list of SQL identifier types.
Constant
Description
QSqlDriver.FieldName
A SQL field name
QSqlDriver.TableName
A SQL table name
- PySide6.QtSql.QSqlDriver.NotificationSource#
This enum contains a list of SQL notification sources.
Constant
Description
QSqlDriver.UnknownSource
The notification source is unknown
QSqlDriver.SelfSource
The notification source is this connection
QSqlDriver.OtherSource
The notification source is another connection
- PySide6.QtSql.QSqlDriver.DbmsType#
- PySide6.QtSql.QSqlDriver.beginTransaction()#
- Return type:
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
- PySide6.QtSql.QSqlDriver.cancelQuery()#
- Return type:
bool
- abstract PySide6.QtSql.QSqlDriver.close()#
Derived classes must reimplement this pure virtual function in order to close the database connection. Return true on success, false on failure.
- PySide6.QtSql.QSqlDriver.commitTransaction()#
- Return type:
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
- abstract PySide6.QtSql.QSqlDriver.createResult()#
- Return type:
Creates an empty SQL result on the database. Derived classes must reimplement this function and return a QSqlResult
object appropriate for their database to the caller.
- PySide6.QtSql.QSqlDriver.escapeIdentifier(identifier, type)#
- Parameters:
identifier – str
type –
IdentifierType
- Return type:
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
- PySide6.QtSql.QSqlDriver.formatValue(field[, trimStrings=false])#
- Parameters:
field –
PySide6.QtSql.QSqlField
trimStrings – bool
- Return type:
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). IftrimStrings
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 bytearray 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
toString()
- abstract PySide6.QtSql.QSqlDriver.hasFeature(f)#
- Parameters:
f –
DriverFeature
- Return type:
bool
Returns true
if the driver supports feature feature
; otherwise returns false
.
Note that some databases need to be open()
before this can be determined.
See also
DriverFeature
- PySide6.QtSql.QSqlDriver.isIdentifierEscaped(identifier, type)#
- Parameters:
identifier – str
type –
IdentifierType
- Return type:
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
- PySide6.QtSql.QSqlDriver.isOpen()#
- Return type:
bool
Returns true
if the database connection is open; otherwise returns false.
- PySide6.QtSql.QSqlDriver.isOpenError()#
- Return type:
bool
Returns true
if the there was an error opening the database connection; otherwise returns false
.
- PySide6.QtSql.QSqlDriver.lastError()#
- Return type:
Returns a QSqlError
object which contains information about the last error that occurred on the database.
See also
- PySide6.QtSql.QSqlDriver.maximumIdentifierLength(type)#
- Parameters:
type –
IdentifierType
- Return type:
int
Returns the maximum length for the identifier type
according to the database settings. Returns INT_MAX by default if the is no maximum for the database.
- PySide6.QtSql.QSqlDriver.notification(name, source, payload)#
- Parameters:
name – str
source –
NotificationSource
payload – object
This signal is emitted when the database posts an event notification that the driver subscribes to. name
identifies the event notification, source
indicates the signal source, payload
holds the extra data optionally delivered with the notification.
See also
- PySide6.QtSql.QSqlDriver.numericalPrecisionPolicy()#
- Return type:
Returns the current default precision policy for the database connection.
See also
NumericalPrecisionPolicy
setNumericalPrecisionPolicy()
numericalPrecisionPolicy()
setNumericalPrecisionPolicy()
- abstract PySide6.QtSql.QSqlDriver.open(db[, user=""[, password=""[, host=""[, port=-1[, connOpts=""]]]]])#
- Parameters:
db – str
user – str
password – str
host – str
port – int
connOpts – str
- Return type:
bool
Derived classes must reimplement this pure virtual function to open a database connection on database db
, using user name user
, password password
, host host
, port port
and connection options options
.
The function must return true on success and false on failure.
See also
- PySide6.QtSql.QSqlDriver.primaryIndex(tableName)#
- Parameters:
tableName – str
- Return type:
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.
- PySide6.QtSql.QSqlDriver.record(tableName)#
- Parameters:
tableName – str
- Return type:
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.
- PySide6.QtSql.QSqlDriver.rollbackTransaction()#
- Return type:
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
- PySide6.QtSql.QSqlDriver.setLastError(e)#
- Parameters:
This function is used to set the value of the last error, error
, that occurred on the database.
See also
- PySide6.QtSql.QSqlDriver.setNumericalPrecisionPolicy(precisionPolicy)#
- Parameters:
precisionPolicy –
NumericalPrecisionPolicy
Sets the default numerical precision policy used by queries created by this driver to precisionPolicy
.
Note: Setting the default precision policy to precisionPolicy
doesn’t affect any currently active queries.
See also
NumericalPrecisionPolicy
numericalPrecisionPolicy()
setNumericalPrecisionPolicy()
numericalPrecisionPolicy()
- PySide6.QtSql.QSqlDriver.setOpen(o)#
- Parameters:
o – 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
- PySide6.QtSql.QSqlDriver.setOpenError(e)#
- Parameters:
e – 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
- PySide6.QtSql.QSqlDriver.sqlStatement(type, tableName, rec, preparedStatement)#
- Parameters:
type –
StatementType
tableName – str
rec –
PySide6.QtSql.QSqlRecord
preparedStatement – bool
- Return type:
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.
- PySide6.QtSql.QSqlDriver.stripDelimiters(identifier, type)#
- Parameters:
identifier – str
type –
IdentifierType
- Return type:
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
- PySide6.QtSql.QSqlDriver.subscribeToNotification(name)#
- Parameters:
name – str
- Return type:
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,
- PySide6.QtSql.QSqlDriver.subscribedToNotifications()#
- Return type:
list of strings
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,
- PySide6.QtSql.QSqlDriver.tables(tableType)#
- Parameters:
tableType –
TableType
- Return type:
list of strings
Returns a list of the names of the tables in the database. The default implementation returns an empty list.
The tableType
argument describes what types of tables should be returned. Due to binary compatibility, the string contains the value of the enum QSql::TableTypes as text. An empty string should be treated as Tables
for backward compatibility.
- PySide6.QtSql.QSqlDriver.unsubscribeFromNotification(name)#
- Parameters:
name – str
- Return type:
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,