QSqlQueryModel ¶

概要 ¶

详细描述 ¶

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 。例如：

QSqlQueryModel *model = new QSqlQueryModel;
model->setQuery("SELECT name, salary FROM employee");
model->setHeaderData(0, Qt::Horizontal, tr("Name"));
model->setHeaderData(1, Qt::Horizontal, tr("Salary"));
QTableView *view = new 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 SELECT query. Since salary is the 2nd column (or column index 1), 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.

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() 了解更多信息。

另请参阅

QSqlTableModel QSqlRelationalTableModel QSqlQuery 模型/视图编程 Query Model Example

class QSqlQueryModel ( [ parent=None ] ) ¶

param parent

QObject

Creates an empty QSqlQueryModel 采用给定 parent .

PySide2.QtSql.QSqlQueryModel. beginInsertColumns ( parent , first , last ) ¶

参数

• parent – QModelIndex

• first – int

• last – int

PySide2.QtSql.QSqlQueryModel. beginInsertRows ( parent , first , last ) ¶

参数

• parent – QModelIndex

• first – int

• last – int

PySide2.QtSql.QSqlQueryModel. beginRemoveColumns ( parent , first , last ) ¶

参数

• parent – QModelIndex

• first – int

• last – int

PySide2.QtSql.QSqlQueryModel. beginRemoveRows ( parent , first , last ) ¶

参数

• parent – QModelIndex

• first – int

• last – int

PySide2.QtSql.QSqlQueryModel. beginResetModel ( ) ¶

PySide2.QtSql.QSqlQueryModel. clear ( ) ¶

Clears the model and releases any acquired resource.

PySide2.QtSql.QSqlQueryModel. endInsertColumns ( ) ¶

PySide2.QtSql.QSqlQueryModel. endInsertRows ( ) ¶

PySide2.QtSql.QSqlQueryModel. endRemoveColumns ( ) ¶

PySide2.QtSql.QSqlQueryModel. endRemoveRows ( ) ¶

PySide2.QtSql.QSqlQueryModel. endResetModel ( ) ¶

PySide2.QtSql.QSqlQueryModel. indexInQuery ( item ) ¶

参数

item – QModelIndex

返回类型

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.

另请参阅

indexInQuery() insertColumns() removeColumns()

PySide2.QtSql.QSqlQueryModel. lastError ( ) ¶

返回类型

QSqlError

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

另请参阅

setLastError() query()

PySide2.QtSql.QSqlQueryModel. query ( ) ¶

返回类型

QSqlQuery

返回 QSqlQuery associated with this model.

另请参阅

setQuery()

PySide2.QtSql.QSqlQueryModel. queryChange ( ) ¶

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

query() returns the new query.

另请参阅

query() setQuery()

PySide2.QtSql.QSqlQueryModel. record ( ) ¶

返回类型

QSqlRecord

这是重载函数。

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.

另请参阅

isEmpty()

PySide2.QtSql.QSqlQueryModel. record ( row ) ¶

参数

row – int

返回类型

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.

另请参阅

isEmpty()

PySide2.QtSql.QSqlQueryModel. setLastError ( error ) ¶

参数

error – QSqlError

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

另请参阅

lastError()

PySide2.QtSql.QSqlQueryModel. setQuery ( query ) ¶

参数

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.

注意

Calling will remove any inserted columns.

另请参阅

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

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

参数

• query – unicode

• db – QSqlDatabase

这是重载函数。

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.

范例：

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

另请参阅

query() queryChange() lastError()