QSqlQueryModel

The QSqlQueryModel class provides a read-only data model for SQL result sets. More…

Inherited by: QSqlRelationalTableModel, QSqlTableModel

Synopsis

Functions

• def lastError ()

• def query ()

• def record ()

• def record (row)

• def setLastError (error)

• def setQuery (query)

• def setQuery (query[, db=QSqlDatabase()])

Virtual functions

• def clear ()

• def indexInQuery (item)

• def queryChange ()

Detailed Description

QSqlQueryModel is a high-level interface for executing SQL statements and traversing the result set. It is built on top of the lower-level QSqlQuery and can be used to provide data to view classes such as QTableView . For example:

model =  QSqlQueryModel()
model.setQuery("SELECT name, salary FROM employee")
model.setHeaderData(0, Qt.Horizontal, tr("Name"))
model.setHeaderData(1, Qt.Horizontal, tr("Salary"))


view =  QTableView()

view.setModel(model)

view.show()

We set the model’s query, then we set up the labels displayed in the view header.

QSqlQueryModel can also be used to access a database programmatically, without binding it to a view:

model = QSqlQueryModel()
model.setQuery("SELECT * FROM employee")
salary = model.record(4).value("salary")

The code snippet above extracts the salary field from record 4 in the result set of the query SELECT * from employee . Assuming that salary is column 2, we can rewrite the last line as follows:

salary = model.data(model.index(4, 2))

The model is read-only by default. To make it read-write, you must subclass it and reimplement setData() and flags() . Another option is to use QSqlTableModel , which provides a read-write model based on a single database table.

The querymodel example illustrates how to use QSqlQueryModel to display the result of a query. It also shows how to subclass QSqlQueryModel to customize the contents of the data before showing it to the user, and how to create a read-write model based on QSqlQueryModel .

If the database doesn’t return the number of selected rows in a query, the model will fetch rows incrementally. See fetchMore() for more information.

See also

QSqlTableModel QSqlRelationalTableModel QSqlQuery Model/View Programming Query Model Example

class QSqlQueryModel([parent=None])

param parent

QObject

Creates an empty QSqlQueryModel with the given parent .

PySide2.QtSql.QSqlQueryModel.clear()

Clears the model and releases any acquired resource.

PySide2.QtSql.QSqlQueryModel.indexInQuery(item)

Parameters

item – QModelIndex

Return type

QModelIndex

Returns the index of the value in the database result set for the given item in the model.

The return value is identical to item if no columns or rows have been inserted, removed, or moved around.

Returns an invalid model index if item is out of bounds or if item does not point to a value in the result set.

See also

indexInQuery() insertColumns() removeColumns()

PySide2.QtSql.QSqlQueryModel.lastError()

Return type

QSqlError

Returns information about the last error that occurred on the database.

See also

setLastError() query()

PySide2.QtSql.QSqlQueryModel.query()

Return type

QSqlQuery

Returns the QSqlQuery associated with this model.

See also

setQuery()

PySide2.QtSql.QSqlQueryModel.queryChange()

This virtual function is called whenever the query changes. The default implementation does nothing.

query() returns the new query.

See also

query() setQuery()

PySide2.QtSql.QSqlQueryModel.record(row)

Parameters

row – int

Return type

QSqlRecord

Returns the record containing information about the fields of the current query. If row is the index of a valid row, the record will be populated with values from that row.

If the model is not initialized, an empty record will be returned.

See also

isEmpty()

PySide2.QtSql.QSqlQueryModel.record()

Return type

QSqlRecord

This is an overloaded function.

Returns an empty record containing information about the fields of the current query.

If the model is not initialized, an empty record will be returned.

See also

isEmpty()

PySide2.QtSql.QSqlQueryModel.setLastError(error)

Parameters

error – QSqlError

Protected function which allows derived classes to set the value of the last error that occurred on the database to error .

See also

lastError()

PySide2.QtSql.QSqlQueryModel.setQuery(query)

Parameters

query – QSqlQuery

Resets the model and sets the data provider to be the given query . Note that the query must be active and must not be isForwardOnly().

lastError() can be used to retrieve verbose information if there was an error setting the query.

Note

Calling will remove any inserted columns.

See also

query() isActive() setForwardOnly() lastError()

PySide2.QtSql.QSqlQueryModel.setQuery(query[, db=QSqlDatabase()])

Parameters

• query – unicode

• db – QSqlDatabase

This is an overloaded function.

Executes the query query for the given database connection db . If no database (or an invalid database) is specified, the default connection is used.

lastError() can be used to retrieve verbose information if there was an error setting the query.

Example:

model = QSqlQueryModel()
model.setQuery("select * from MyTable")
if model.lastError().isValid():
    print model.lastError()

See also

query() queryChange() lastError()