QSqlCursor man page on aLinux

Man page or keyword search:  
man Server   7435 pages
apropos Keyword Search (all sections)
Output format
aLinux logo
[printable version]

QSqlCursor(3qt)						       QSqlCursor(3qt)

NAME
       QSqlCursor - Browsing and editing of SQL tables and views

SYNOPSIS
       #include <qsqlcursor.h>

       Inherits QSqlRecord and QSqlQuery.

       Inherited by QSqlSelectCursor.

   Public Members
       QSqlCursor ( const QString & name = QString::null, bool autopopulate =
	   TRUE, QSqlDatabase * db = 0 )
       QSqlCursor ( const QSqlCursor & other )
       QSqlCursor & operator= ( const QSqlCursor & other )
       ~QSqlCursor ()
       enum Mode { ReadOnly = 0, Insert = 1, Update = 2, Delete = 4, Writable
	   = 7 }
       virtual QSqlIndex primaryIndex ( bool setFromCursor = TRUE ) const
       virtual QSqlIndex index ( const QStringList & fieldNames ) const
       QSqlIndex index ( const QString & fieldName ) const
       QSqlIndex index ( const char * fieldName ) const
       virtual void setPrimaryIndex ( const QSqlIndex & idx )
       virtual void append ( const QSqlFieldInfo & fieldInfo )
       virtual void insert ( int pos, const QSqlFieldInfo & fieldInfo )
       virtual void remove ( int pos )
       virtual void clear ()
       virtual void setGenerated ( const QString & name, bool generated )
       virtual void setGenerated ( int i, bool generated )
       virtual QSqlRecord * editBuffer ( bool copy = FALSE )
       virtual QSqlRecord * primeInsert ()
       virtual QSqlRecord * primeUpdate ()
       virtual QSqlRecord * primeDelete ()
       virtual int insert ( bool invalidate = TRUE )
       virtual int update ( bool invalidate = TRUE )
       virtual int del ( bool invalidate = TRUE )
       virtual void setMode ( int mode )
       int mode () const
       virtual void setCalculated ( const QString & name, bool calculated )
       bool isCalculated ( const QString & name ) const
       virtual void setTrimmed ( const QString & name, bool trim )
       bool isTrimmed ( const QString & name ) const
       bool isReadOnly () const
       bool canInsert () const
       bool canUpdate () const
       bool canDelete () const
       bool select ()
       bool select ( const QSqlIndex & sort )
       bool select ( const QSqlIndex & filter, const QSqlIndex & sort )
       virtual bool select ( const QString & filter, const QSqlIndex & sort =
	   QSqlIndex ( ) )
       virtual void setSort ( const QSqlIndex & sort )
       QSqlIndex sort () const
       virtual void setFilter ( const QString & filter )
       QString filter () const
       virtual void setName ( const QString & name, bool autopopulate = TRUE )
       QString name () const
       bool isNull ( int i ) const
       bool isNull ( const QString & name ) const

   Protected Members
       virtual QVariant calculateField ( const QString & name )
       virtual int update ( const QString & filter, bool invalidate = TRUE )
       virtual int del ( const QString & filter, bool invalidate = TRUE )
       virtual QString toString ( const QString & prefix, QSqlField * field,
	   const QString & fieldSep ) const
       virtual QString toString ( QSqlRecord * rec, const QString & prefix,
	   const QString & fieldSep, const QString & sep ) const
       virtual QString toString ( const QSqlIndex & i, QSqlRecord * rec, const
	   QString & prefix, const QString & fieldSep, const QString & sep )
	   const

DESCRIPTION
       The QSqlCursor class provides browsing and editing of SQL tables and
       views.

       A QSqlCursor is a database record (see QSqlRecord) that corresponds to
       a table or view within an SQL database (see QSqlDatabase). There are
       two buffers in a cursor, one used for browsing and one used for editing
       records. Each buffer contains a list of fields which correspond to the
       fields in the table or view.

       When positioned on a valid record, the browse buffer contains the
       values of the current record's fields from the database. The edit
       buffer is separate, and is used for editing existing records and
       inserting new records.

       For browsing data, a cursor must first select() data from the database.
       After a successful select() the cursor is active (isActive() returns
       TRUE), but is initially not positioned on a valid record (isValid()
       returns FALSE). To position the cursor on a valid record, use one of
       the navigation functions, next(), prev(), first(), last(), or seek().
       Once positioned on a valid record, data can be retrieved from the
       browse buffer using value(). If a navigation function is not
       successful, it returns FALSE, the cursor will no longer be positioned
       on a valid record and the values returned by value() are undefined.

       For example:

		   QSqlCursor cur( "staff" ); // Specify the table/view name
		   cur.select(); // We'll retrieve every record
		   while ( cur.next() ) {
		       qDebug( cur.value( "id" ).toString() + ": " +
			       cur.value( "surname" ).toString() + " " +
			       cur.value( "salary" ).toString() );
		   }

       In the above example, a cursor is created specifying a table or view
       name in the database. Then, select() is called, which can be optionally
       parameterised to filter and order the records retrieved. Each record in
       the cursor is retrieved using next(). When next() returns FALSE, there
       are no more records to process, and the loop terminates.

       For editing records (rows of data), a cursor contains a separate edit
       buffer which is independent of the fields used when browsing. The
       functions insert(), update() and del() operate on the edit buffer. This
       allows the cursor to be repositioned to other records while
       simultaneously maintaining a separate buffer for edits. You can get a
       pointer to the edit buffer using editBuffer(). The primeInsert(),
       primeUpdate() and primeDelete() functions also return a pointer to the
       edit buffer and prepare it for insert, update and delete respectively.
       Edit operations only affect a single row at a time. Note that update()
       and del() require that the table or view contain a primaryIndex() to
       ensure that edit operations affect a unique record within the database.

       For example:

		   QSqlCursor cur( "prices" );
		   cur.select( "id=202" );
		   if ( cur.next() ) {
		       QSqlRecord *buffer = cur.primeUpdate();
		       double price = buffer->value( "price" ).toDouble();
		       double newprice = price * 1.05;
		       buffer->setValue( "price", newprice );
		       cur.update();
		   }

       To edit an existing database record, first move to the record you wish
       to update. Call primeUpdate() to get the pointer to the cursor's edit
       buffer. Then use this pointer to modify the values in the edit buffer.
       Finally, call update() to save the changes to the database. The values
       in the edit buffer will be used to locate the appropriate record when
       updating the database (see primaryIndex()).

       Similarly, when deleting an existing database record, first move to the
       record you wish to delete. Then, call primeDelete() to get the pointer
       to the edit buffer. Finally, call del() to delete the record from the
       database. Again, the values in the edit buffer will be used to locate
       and delete the appropriate record.

       To insert a new record, call primeInsert() to get the pointer to the
       edit buffer. Use this pointer to populate the edit buffer with new
       values and then insert() the record into the database.

       After calling insert(), update() or del(), the cursor is no longer
       positioned on a valid record and can no longer be navigated (isValid()
       return FALSE). The reason for this is that any changes made to the
       database will not be visible until select() is called to refresh the
       cursor. You can change this behavior by passing FALSE to insert(),
       update() or del() which will prevent the cursor from becoming invalid.
       The edits will still not be visible when navigating the cursor until
       select() is called.

       QSqlCursor contains virtual methods which allow editing behavior to be
       customized by subclasses. This allows custom cursors to be created that
       encapsulate the editing behavior of a database table for an entire
       application. For example, a cursor can be customized to always auto-
       number primary index fields, or provide fields with suitable default
       values, when inserting new records. QSqlCursor generates SQL statements
       which are sent to the database engine; you can control which fields are
       included in these statements using setGenerated().

       Note that QSqlCursor does not inherit from QObject. This means that you
       are responsible for destroying instances of this class yourself.
       However if you create a QSqlCursor and use it in a QDataTable,
       QDataBrowser or a QDataView these classes will usually take ownership
       of the cursor and destroy it when they don't need it anymore. The
       documentation for QDataTable, QDataBrowser and QDataView explicitly
       states which calls take ownership of the cursor.

       See also Database Classes.

   Member Type Documentation
QSqlCursor::Mode
       This enum type describes how QSqlCursor operates on records in the
       database.

       QSqlCursor::ReadOnly - the cursor can only SELECT records from the
       database.

       QSqlCursor::Insert - the cursor can INSERT records into the database.

       QSqlCursor::Update - the cursor can UPDATE records in the database.

       QSqlCursor::Delete - the cursor can DELETE records from the database.

       QSqlCursor::Writable - the cursor can INSERT, UPDATE and DELETE records
       in the database.

MEMBER FUNCTION DOCUMENTATION
QSqlCursor::QSqlCursor ( const QString & name = QString::null, bool
       autopopulate = TRUE, QSqlDatabase * db = 0 )
       Constructs a cursor on database db using table or view name.

       If autopopulate is TRUE (the default), the name of the cursor must
       correspond to an existing table or view name in the database so that
       field information can be automatically created. If the table or view
       does not exist, the cursor will not be functional.

       The cursor is created with an initial mode of QSqlCursor::Writable
       (meaning that records can be inserted, updated or deleted using the
       cursor). If the cursor does not have a unique primary index, update and
       deletes cannot be performed.

       Note that autopopulate refers to populating the cursor with meta-data,
       e.g. the names of the table's fields, not with retrieving data. The
       select() function is used to populate the cursor with data.

       See also setName() and setMode().

QSqlCursor::QSqlCursor ( const QSqlCursor & other )
       Constructs a copy of other.

QSqlCursor::~QSqlCursor ()
       Destroys the object and frees any allocated resources.

void QSqlCursor::append ( const QSqlFieldInfo & fieldInfo ) [virtual]
       Append a copy of field fieldInfo to the end of the cursor. Note that
       all references to the cursor edit buffer become invalidated.

QVariant QSqlCursor::calculateField ( const QString & name ) [virtual
       protected]
       Protected virtual function which is called whenever a field needs to be
       calculated. If calculated fields are being used, derived classes must
       reimplement this function and return the appropriate value for field
       name. The default implementation returns an invalid QVariant.

       See also setCalculated().

       Examples:

bool QSqlCursor::canDelete () const
       Returns TRUE if the cursor will perform deletes; otherwise returns
       FALSE.

       See also setMode().

bool QSqlCursor::canInsert () const
       Returns TRUE if the cursor will perform inserts; otherwise returns
       FALSE.

       See also setMode().

bool QSqlCursor::canUpdate () const
       Returns TRUE if the cursor will perform updates; otherwise returns
       FALSE.

       See also setMode().

void QSqlCursor::clear () [virtual]
       Removes all fields from the cursor. Note that all references to the
       cursor edit buffer become invalidated.

       Reimplemented from QSqlRecord.

int QSqlCursor::del ( bool invalidate = TRUE ) [virtual]
       Deletes a record from the database using the cursor's primary index and
       the contents of the cursor edit buffer. Returns the number of records
       which were deleted. For error information, use lastError().

       Only records which meet the filter criteria specified by the cursor's
       primary index are deleted. If the cursor does not contain a primary
       index, no delete is performed and 0 is returned. If invalidate is TRUE
       (the default), the current cursor can no longer be navigated. A new
       select() call must be made before you can move to a valid record. For
       example:

		   QSqlCursor cur( "prices" );
		   cur.select( "id=999" );
		   if ( cur.next() ) {
		       cur.primeDelete();
		       cur.del();
		   }

       In the above example, a cursor is created on the 'prices' table and
       positioned to the record to be deleted. First primeDelete() is called
       to populate the edit buffer with the current cursor values, e.g. with
       an id of 999, and then del() is called to actually delete the record
       from the database. Remember: all edit operations (insert(), update()
       and delete()) operate on the contents of the cursor edit buffer and not
       on the contents of the cursor itself.

       See also primeDelete(), setMode(), and lastError().

       Example: sql/overview/delete/main.cpp.

int QSqlCursor::del ( const QString & filter, bool invalidate = TRUE )
       [virtual protected]
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Deletes the current cursor record from the database using the filter
       filter. Only records which meet the filter criteria are deleted.
       Returns the number of records which were deleted. If invalidate is TRUE
       (the default), the current cursor can no longer be navigated. A new
       select() call must be made before you can move to a valid record. For
       error information, use lastError().

       The filter is an SQL WHERE clause, e.g. id=500.

       See also setMode() and lastError().

QSqlRecord * QSqlCursor::editBuffer ( bool copy = FALSE ) [virtual]
       Returns the current internal edit buffer. If copy is TRUE (the default
       is FALSE), the current cursor field values are first copied into the
       edit buffer. The edit buffer is valid as long as the cursor remains
       valid. The cursor retains ownership of the returned pointer, so it must
       not be deleted or modified.

       See also primeInsert(), primeUpdate(), and primeDelete().

QString QSqlCursor::filter () const
       Returns the current filter, or an empty string if there is no current
       filter.

QSqlIndex QSqlCursor::index ( const QStringList & fieldNames ) const [virtual]

       Returns an index composed of fieldNames, all in ASCending order. Note
       that all field names must exist in the cursor, otherwise an empty index
       is returned.

       See also QSqlIndex.

       Examples:

QSqlIndex QSqlCursor::index ( const QString & fieldName ) const
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Returns an index based on fieldName.

QSqlIndex QSqlCursor::index ( const char * fieldName ) const
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Returns an index based on fieldName.

void QSqlCursor::insert ( int pos, const QSqlFieldInfo & fieldInfo ) [virtual]

       Insert a copy of fieldInfo at position pos. If a field already exists
       at pos, it is removed. Note that all references to the cursor edit
       buffer become invalidated.

       Examples:

int QSqlCursor::insert ( bool invalidate = TRUE ) [virtual]
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Inserts the current contents of the cursor's edit record buffer into
       the database, if the cursor allows inserts. Returns the number of rows
       affected by the insert. For error information, use lastError().

       If invalidate is TRUE (the default), the cursor will no longer be
       positioned on a valid record and can no longer be navigated. A new
       select() call must be made before navigating to a valid record.

		   QSqlCursor cur( "prices" );
		   QSqlRecord *buffer = cur.primeInsert();
		   buffer->setValue( "id",    53981 );
		   buffer->setValue( "name",  "Thingy" );
		   buffer->setValue( "price", 105.75 );
		   cur.insert();

       In the above example, a cursor is created on the 'prices' table and a
       pointer to the insert buffer is aquired using primeInsert(). Each
       field's value is set to the desired value and then insert() is called
       to insert the data into the database. Remember: all edit operations
       (insert(), update() and delete()) operate on the contents of the cursor
       edit buffer and not on the contents of the cursor itself.

       See also setMode() and lastError().

bool QSqlCursor::isCalculated ( const QString & name ) const
       Returns TRUE if the field name exists and is calculated; otherwise
       returns FALSE.

       See also setCalculated().

bool QSqlCursor::isNull ( int i ) const
       Returns TRUE if the field i is NULL or if there is no field at position
       i; otherwise returns FALSE.

       This is the same as calling QSqlRecord::isNull( i )

bool QSqlCursor::isNull ( const QString & name ) const
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Returns TRUE if the field called name is NULL or if there is no field
       called name; otherwise returns FALSE.

       This is the same as calling QSqlRecord::isNull( name )

bool QSqlCursor::isReadOnly () const
       Returns TRUE if the cursor is read-only; otherwise returns FALSE. The
       default is FALSE. Read-only cursors cannot be edited using insert(),
       update() or del().

       See also setMode().

bool QSqlCursor::isTrimmed ( const QString & name ) const
       Returns TRUE if the field name exists and is trimmed; otherwise returns
       FALSE.

       When a trimmed field of type string or cstring is read from the
       database any trailing (right-most) spaces are removed.

       See also setTrimmed().

int QSqlCursor::mode () const
       Returns the current cursor mode.

       See also setMode().

QString QSqlCursor::name () const
       Returns the name of the cursor.

QSqlCursor & QSqlCursor::operator= ( const QSqlCursor & other )
       Sets the cursor equal to other.

QSqlIndex QSqlCursor::primaryIndex ( bool setFromCursor = TRUE ) const
       [virtual]
       Returns the primary index associated with the cursor as defined in the
       database, or an empty index if there is no primary index. If
       setFromCursor is TRUE (the default), the index fields are populated
       with the corresponding values in the cursor's current record.

QSqlRecord * QSqlCursor::primeDelete () [virtual]
       This function primes the edit buffer's field values for delete and
       returns the edit buffer. The default implementation copies the field
       values from the current cursor record into the edit buffer (therefore,
       this function is equivalent to calling editBuffer( TRUE ) ). The cursor
       retains ownership of the returned pointer, so it must not be deleted or
       modified.

       See also editBuffer() and del().

       Example: sql/overview/delete/main.cpp.

QSqlRecord * QSqlCursor::primeInsert () [virtual]
       This function primes the edit buffer's field values for insert and
       returns the edit buffer. The default implementation clears all field
       values in the edit buffer. The cursor retains ownership of the returned
       pointer, so it must not be deleted or modified.

       See also editBuffer() and insert().

       Examples:

QSqlRecord * QSqlCursor::primeUpdate () [virtual]
       This function primes the edit buffer's field values for update and
       returns the edit buffer. The default implementation copies the field
       values from the current cursor record into the edit buffer (therefore,
       this function is equivalent to calling editBuffer( TRUE ) ). The cursor
       retains ownership of the returned pointer, so it must not be deleted or
       modified.

       See also editBuffer() and update().

       Examples:

void QSqlCursor::remove ( int pos ) [virtual]
       Removes the field at pos. If pos does not exist, nothing happens. Note
       that all references to the cursor edit buffer become invalidated.

       Reimplemented from QSqlRecord.

bool QSqlCursor::select ( const QString & filter, const QSqlIndex & sort =
       QSqlIndex ( ) ) [virtual]
       Selects all fields in the cursor from the database matching the filter
       criteria filter. The data is returned in the order specified by the
       index sort. Returns TRUE if the data was successfully selected;
       otherwise returns FALSE.

       The filter is a string containing a SQL WHERE clause but without the
       'WHERE' keyword. The cursor is initially positioned at an invalid row
       after this function is called. To move to a valid row, use seek(),
       first(), last(), prev() or next().

       Example:

	   QSqlCursor cur( "Employee" ); // Use the Employee table or view
	   cur.select( "deptno=10" ); // select all records in department 10
	   while( cur.next() ) {
	       ... // process data
	   }
	   ...
	   // select records in other departments, ordered by department number
	   cur.select( "deptno>10", cur.index( "deptno" ) );
	   ...

       The filter will apply to any subsequent select() calls that do not
       explicitly specify another filter. Similarly the sort will apply to any
       subsequent select() calls that do not explicitly specify another sort.

	   QSqlCursor cur( "Employee" );
	   cur.select( "deptno=10" ); // select all records in department 10
	   while( cur.next() ) {
	       ... // process data
	   }
	   ...
	   cur.select(); // re-selects all records in department 10
	   ...

       Examples:

bool QSqlCursor::select ()
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Selects all fields in the cursor from the database. The rows are
       returned in the order specified by the last call to setSort() or the
       last call to select() that specified a sort, whichever is the most
       recent. If there is no current sort, the order in which the rows are
       returned is undefined. The records are filtered according to the filter
       specified by the last call to setFilter() or the last call to select()
       that specified a filter, whichever is the most recent. If there is no
       current filter, all records are returned. The cursor is initially
       positioned at an invalid row. To move to a valid row, use seek(),
       first(), last(), prev() or next().

       See also setSort() and setFilter().

bool QSqlCursor::select ( const QSqlIndex & sort )
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Selects all fields in the cursor from the database. The data is
       returned in the order specified by the index sort. The records are
       filtered according to the filter specified by the last call to
       setFilter() or the last call to select() that specified a filter,
       whichever is the most recent. The cursor is initially positioned at an
       invalid row. To move to a valid row, use seek(), first(), last(),
       prev() or next().

bool QSqlCursor::select ( const QSqlIndex & filter, const QSqlIndex & sort )
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Selects all fields in the cursor matching the filter index filter. The
       data is returned in the order specified by the index sort. The filter
       index works by constructing a WHERE clause using the names of the
       fields from the filter and their values from the current cursor record.
       The cursor is initially positioned at an invalid row. To move to a
       valid row, use seek(), first(), last(), prev() or next(). This function
       is useful, for example, for retrieving data based upon a table's
       primary index:

	   QSqlCursor cur( "Employee" );
	   QSqlIndex pk = cur.primaryIndex();
	   cur.setValue( "id", 10 );
	   cur.select( pk, pk ); // generates "SELECT ... FROM Employee WHERE id=10 ORDER BY id"
	   ...

       In this example the QSqlIndex, pk, is used for two different purposes.
       When used as the filter (first) argument, the field names it contains
       are used to construct the WHERE clause, each set to the current cursor
       value, WHERE id=10, in this case. When used as the sort (second)
       argument the field names it contains are used for the ORDER BY clause,
       ORDER BY id in this example.

void QSqlCursor::setCalculated ( const QString & name, bool calculated )
       [virtual]
       Sets field name to calculated. If the field name does not exist,
       nothing happens. The value of a calculated field is set by the
       calculateField() virtual function which you must reimplement (or the
       field value will be an invalid QVariant). Calculated fields do not
       appear in generated SQL statements sent to the database.

       See also calculateField() and QSqlRecord::setGenerated().

void QSqlCursor::setFilter ( const QString & filter ) [virtual]
       Sets the current filter to filter. Note that no new records are
       selected. To select new records, use select(). The filter will apply to
       any subsequent select() calls that do not explicitly specify a filter.

       The filter is a SQL WHERE clause without the keyword 'WHERE', e.g.
       name='Dave' which will be processed by the DBMS.

void QSqlCursor::setGenerated ( const QString & name, bool generated )
       [virtual]
       Sets the generated flag for the field name to generated. If the field
       does not exist, nothing happens. Only fields that have generated set to
       TRUE are included in the SQL that is generated by insert(), update() or
       del().

       See also isGenerated().

       Reimplemented from QSqlRecord.

void QSqlCursor::setGenerated ( int i, bool generated ) [virtual]
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Sets the generated flag for the field i to generated.

       See also isGenerated().

       Reimplemented from QSqlRecord.

void QSqlCursor::setMode ( int mode ) [virtual]
       Sets the cursor mode to mode. This value can be an OR'ed combination of
       QSqlCursor::Mode values. The default mode for a cursor is
       QSqlCursor::Writable.

	   QSqlCursor cur( "Employee" );
	   cur.setMode( QSqlCursor::Writable ); // allow insert/update/delete
	   ...
	   cur.setMode( QSqlCursor::Insert | QSqlCursor::Update ); // allow inserts and updates only
	   ...
	   cur.setMode( QSqlCursor::ReadOnly ); // no inserts/updates/deletes allowed

void QSqlCursor::setName ( const QString & name, bool autopopulate = TRUE )
       [virtual]
       Sets the name of the cursor to name. If autopopulate is TRUE (the
       default), the name must correspond to a valid table or view name in the
       database. Also, note that all references to the cursor edit buffer
       become invalidated when fields are auto-populated. See the QSqlCursor
       constructor documentation for more information.

void QSqlCursor::setPrimaryIndex ( const QSqlIndex & idx ) [virtual]
       Sets the primary index associated with the cursor to the index idx.
       Note that this index must contain a field or set of fields which
       identify a unique record within the underlying database table or view
       so that update() and del() will execute as expected.

       See also update() and del().

void QSqlCursor::setSort ( const QSqlIndex & sort ) [virtual]
       Sets the current sort to sort. Note that no new records are selected.
       To select new records, use select(). The sort will apply to any
       subsequent select() calls that do not explicitly specify a sort.

void QSqlCursor::setTrimmed ( const QString & name, bool trim ) [virtual]
       Sets field name's trimmed status to trim. If the field name does not
       exist, nothing happens.

       When a trimmed field of type string or cstring is read from the
       database any trailing (right-most) spaces are removed.

       See also isTrimmed() and QVariant.

QSqlIndex QSqlCursor::sort () const
       Returns the current sort, or an empty index if there is no current
       sort.

QString QSqlCursor::toString ( QSqlRecord * rec, const QString & prefix, const
       QString & fieldSep, const QString & sep ) const [virtual protected]
       Returns a formatted string composed of all the fields in rec. Each
       field is composed of the prefix (e.g. table or view name)," prefix is
       empty then each field will begin with the field name. The fields are
       then joined together separated by sep. Fields where isGenerated()
       returns FALSE are not included. This function is useful for generating
       SQL statements.

QString QSqlCursor::toString ( const QString & prefix, QSqlField * field,
       const QString & fieldSep ) const [virtual protected]
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Returns a formatted string composed of the prefix (e.g. table or view
       name), ".", the field name, the fieldSep and the field value. If the
       prefix is empty then the string will begin with the field name. This
       function is useful for generating SQL statements.

QString QSqlCursor::toString ( const QSqlIndex & i, QSqlRecord * rec, const
       QString & prefix, const QString & fieldSep, const QString & sep ) const
       [virtual protected]
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Returns a formatted string composed of all the fields in the index i.
       Each field is composed of the prefix (e.g. table or view name), ".",
       the field name, the fieldSep and the field value. If the prefix is
       empty then each field will begin with the field name. The field values
       are taken from rec. The fields are then joined together separated by
       sep. Fields where isGenerated() returns FALSE are ignored. This
       function is useful for generating SQL statements.

int QSqlCursor::update ( bool invalidate = TRUE ) [virtual]
       Updates the database with the current contents of the edit buffer.
       Returns the number of records which were updated. For error
       information, use lastError().

       Only records which meet the filter criteria specified by the cursor's
       primary index are updated. If the cursor does not contain a primary
       index, no update is performed and 0 is returned.

       If invalidate is TRUE (the default), the current cursor can no longer
       be navigated. A new select() call must be made before you can move to a
       valid record. For example:

		   QSqlCursor cur( "prices" );
		   cur.select( "id=202" );
		   if ( cur.next() ) {
		       QSqlRecord *buffer = cur.primeUpdate();
		       double price = buffer->value( "price" ).toDouble();
		       double newprice = price * 1.05;
		       buffer->setValue( "price", newprice );
		       cur.update();
		   }

       In the above example, a cursor is created on the 'prices' table and is
       positioned on the record to be updated. Then a pointer to the cursor's
       edit buffer is acquired using primeUpdate(). A new value is calculated
       and placed into the edit buffer with the setValue() call. Finally, an
       update() call is made on the cursor which uses the tables's primary
       index to update the record in the database with the contents of the
       cursor's edit buffer. Remember: all edit operations (insert(), update()
       and delete()) operate on the contents of the cursor edit buffer and not
       on the contents of the cursor itself.

       Note that if the primary index does not uniquely distinguish records
       the database may be changed into an inconsistent state.

       See also setMode() and lastError().

       Example: sql/overview/update/main.cpp.

int QSqlCursor::update ( const QString & filter, bool invalidate = TRUE )
       [virtual protected]
       This is an overloaded member function, provided for convenience. It
       behaves essentially like the above function.

       Updates the database with the current contents of the cursor edit
       buffer using the specified filter. Returns the number of records which
       were updated. For error information, use lastError().

       Only records which meet the filter criteria are updated, otherwise all
       records in the table are updated.

       If invalidate is TRUE (the default), the cursor can no longer be
       navigated. A new select() call must be made before you can move to a
       valid record.

       See also primeUpdate(), setMode(), and lastError().

SEE ALSO
       http://doc.trolltech.com/qsqlcursor.html
       http://www.trolltech.com/faq/tech.html

COPYRIGHT
       Copyright 1992-2007 Trolltech ASA, http://www.trolltech.com.  See the
       license file included in the distribution for a complete license
       statement.

AUTHOR
       Generated automatically from the source code.

BUGS
       If you find a bug in Qt, please report it as described in
       http://doc.trolltech.com/bughowto.html.	Good bug reports help us to
       help you. Thank you.

       The definitive Qt documentation is provided in HTML format; it is
       located at $QTDIR/doc/html and can be read using Qt Assistant or with a
       web browser. This man page is provided as a convenience for those users
       who prefer man pages, although this format is not officially supported
       by Trolltech.

       If you find errors in this manual page, please report them to qt-
       bugs@trolltech.com.  Please include the name of the manual page
       (qsqlcursor.3qt) and the Qt version (3.3.8).

Trolltech AS			2 February 2007		       QSqlCursor(3qt)
[top]

List of man pages available for aLinux

Copyright (c) for man pages and the logo by the respective OS vendor.

For those who want to learn more, the polarhome community provides shell access and support.

[legal] [privacy] [GNU] [policy] [cookies] [netiquette] [sponsors] [FAQ]
Tweet
Polarhome, production since 1999.
Member of Polarhome portal.
Based on Fawad Halim's script.
....................................................................
Vote for polarhome
Free Shell Accounts :: the biggest list on the net