com.trolltech.qt.sql
Class QSqlQueryModel

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.core.QObject
                  extended by com.trolltech.qt.core.QAbstractItemModel
                      extended by com.trolltech.qt.gui.QAbstractTableModel
                          extended by com.trolltech.qt.sql.QSqlQueryModel
All Implemented Interfaces:
QtJambiInterface
Direct Known Subclasses:
QSqlTableModel

public class QSqlQueryModel
extends QAbstractTableModel

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

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

        QSqlQueryModel model = new QSqlQueryModel();
        model.setQuery("SELECT * FROM employee");
        int salary = ((Integer) model.record(4).value("salary")).intValue();
    
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:
        int salary = ((Integer) model.data(model.index(4, 2))).intValue();
    
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 sql/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 amount 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, and Query Model Example.


Nested Class Summary
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9
 
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
 
Fields inherited from class com.trolltech.qt.core.QAbstractItemModel
columnsAboutToBeInserted, columnsAboutToBeRemoved, columnsInserted, columnsRemoved, dataChanged, headerDataChanged, layoutAboutToBeChanged, layoutChanged, modelAboutToBeReset, modelReset, rowsAboutToBeInserted, rowsAboutToBeRemoved, rowsInserted, rowsRemoved
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QSqlQueryModel()
          Creates an empty QSqlQueryModel with the given parent.
QSqlQueryModel(QObject parent)
          Creates an empty QSqlQueryModel with the given parent.
 
Method Summary
 void clear()
          Clears the model and releases any acquired resource.
protected  com.trolltech.qt.core.QModelIndex indexInQuery(com.trolltech.qt.core.QModelIndex item)
          Returns the index of the value in the database result set for the given item in the model.
 QSqlError lastError()
          Returns information about the last error that occurred on the database.
 QSqlQuery query()
          Returns the QSqlQuery associated with this model.
protected  void queryChange()
          This virtual function is called whenever the query changes.
 QSqlRecord record()
          This is an overloaded member function, provided for convenience.
 QSqlRecord record(int row)
          Returns the record containing information about the fields of the current query.
protected  void setLastError(QSqlError error)
          Protected function which allows derived classes to set the value of the last error that occurred on the database to error.
 void setQuery(QSqlQuery query)
          Resets the model and sets the data provider to be the given query.
 void setQuery(java.lang.String query)
          This is an overloaded member function, provided for convenience.
 void setQuery(java.lang.String query, QSqlDatabase db)
          This is an overloaded member function, provided for convenience.
 
Methods inherited from class com.trolltech.qt.core.QAbstractItemModel
beginInsertColumns, beginInsertRows, beginRemoveColumns, beginRemoveRows, buddy, canFetchMore, changePersistentIndex, changePersistentIndexList, columnCount, columnCount, createIndex, createIndex, createIndex, data, data, data, data, dropMimeData, endInsertColumns, endInsertRows, endRemoveColumns, endRemoveRows, fetchMore, flags, hasChildren, hasChildren, hasIndex, hasIndex, headerData, headerData, index, index, insertColumn, insertColumn, insertColumns, insertColumns, insertRow, insertRow, insertRows, insertRows, itemData, match, match, match, match, mimeData, mimeTypes, parent, persistentIndexList, removeColumn, removeColumn, removeColumns, removeColumns, removeRow, removeRow, removeRows, removeRows, reset, revert, rowCount, rowCount, setData, setData, setData, setData, setHeaderData, setHeaderData, setItemData, setSupportedDragActions, setSupportedDragActions, sibling, sort, sort, span, submit, supportedDragActions, supportedDropActions
 
Methods inherited from class com.trolltech.qt.core.QObject
childEvent, children, connectSlotsByName, customEvent, disposeLater, dumpObjectInfo, dumpObjectTree, dynamicPropertyNames, event, eventFilter, findChild, findChild, findChild, findChildren, findChildren, findChildren, findChildren, indexOfProperty, installEventFilter, isWidgetType, killTimer, moveToThread, objectName, parent, properties, property, removeEventFilter, setObjectName, setParent, setProperty, startTimer, timerEvent, toString, userProperty
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
clone, getClass, hashCode, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QSqlQueryModel

public QSqlQueryModel()
Creates an empty QSqlQueryModel with the given parent.


QSqlQueryModel

public QSqlQueryModel(QObject parent)
Creates an empty QSqlQueryModel with the given parent.

Method Detail

indexInQuery

protected com.trolltech.qt.core.QModelIndex indexInQuery(com.trolltech.qt.core.QModelIndex item)
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:
QSqlTableModel::indexInQuery(), insertColumns(), and removeColumns().


lastError

public final QSqlError lastError()
Returns information about the last error that occurred on the database.

See also:
setLastError(), and query().


query

public final QSqlQuery query()
Returns the QSqlQuery associated with this model.

See also:
setQuery().


record

public final QSqlRecord record()
This is an overloaded member function, provided for convenience.

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:
QSqlRecord::isEmpty().


record

public final QSqlRecord record(int row)
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:
QSqlRecord::isEmpty().


setLastError

protected final void setLastError(QSqlError error)
Protected function which allows derived classes to set the value of the last error that occurred on the database to error.

See also:
lastError().


setQuery

public void setQuery(QSqlQuery query)
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.

See also:
query(), QSqlQuery::isActive(), QSqlQuery::setForwardOnly(), and lastError().


setQuery

public final void setQuery(java.lang.String query)
This is an overloaded member function, provided for convenience.

Executes the query query for the given database connection db. If no 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:

    QSqlQueryModel model = new QSqlQueryModel();
    model.setQuery("select * from MyTable");
    if (model.lastError().isValid())
        System.out.println(model.lastError());

See also:
query(), queryChange(), and lastError().


setQuery

public final void setQuery(java.lang.String query,
                           QSqlDatabase db)
This is an overloaded member function, provided for convenience.

Executes the query query for the given database connection db. If no 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:

    QSqlQueryModel model = new QSqlQueryModel();
    model.setQuery("select * from MyTable");
    if (model.lastError().isValid())
        System.out.println(model.lastError());

See also:
query(), queryChange(), and lastError().


clear

public void clear()
Clears the model and releases any acquired resource.


queryChange

protected void queryChange()
This virtual function is called whenever the query changes. The default implementation does nothing.

query() returns the new query.

See also:
query(), and setQuery().