The QSqlResult class provides an abstract interface for accessing data from SQL databases. More...

Inherited by QSqlCachedResult, QSqlNullResult

Public Methods
virtual	~QSqlResult ()

virtual QVariant	handle () const

Protected Types
enum	BindingSyntax

Protected Methods
	QSqlResult (const QSqlDriver *db)

void	addBindValue (const QVariant &value, QSql::ParamType type)

int	at () const

BindingSyntax	bindingSyntax () const

virtual void	bindValue (const QString &placeholder, const QVariant &value, QSql::ParamType type)

virtual void	bindValue (int index, const QVariant &value, QSql::ParamType type)

QSql::ParamType	bindValueType (const QString &placeholder) const

QSql::ParamType	bindValueType (int index) const

QVariant	boundValue (const QString &placeholder) const

QVariant	boundValue (int index) const

int	boundValueCount () const

QString	boundValueName (int index) const

QVector< QVariant > &	boundValues () const

void	clear ()

virtual QVariant	data (int index) = 0

const QSqlDriver *	driver () const

virtual bool	exec ()

QString	executedQuery () const

virtual bool	fetch (int index) = 0

virtual bool	fetchFirst () = 0

virtual bool	fetchLast () = 0

virtual bool	fetchNext ()

virtual bool	fetchPrevious ()

bool	hasOutValues () const

bool	isActive () const

bool	isForwardOnly () const

virtual bool	isNull (int index) = 0

bool	isSelect () const

bool	isValid () const

QSqlError	lastError () const

virtual QVariant	lastInsertId () const

QString	lastQuery () const

virtual int	numRowsAffected () = 0

virtual bool	prepare (const QString &query)

virtual QSqlRecord	record () const

virtual bool	reset (const QString &query) = 0

virtual bool	savePrepare (const QString &query)

virtual void	setActive (bool active)

virtual void	setAt (int index)

virtual void	setForwardOnly (bool forward)

virtual void	setLastError (const QSqlError &error)

virtual void	setQuery (const QString &query)

virtual void	setSelect (bool select)

virtual int	size () = 0

Friends
class	QSqlQuery

Detailed Description

The QSqlResult class provides an abstract interface for accessing data from SQL databases. Normally, you would use QSqlQuery instead of QSqlResult, since QSqlQuery provides a generic wrapper for database-specific implementations of QSqlResult.

If you are implementing your own SQL driver by inheriting from QSqlDriver, provide your own QSqlResult subclass which overrides the pure virtual methods that you need.

See also: QSqlDriver

Member Enumeration Documentation

enum QSqlResult::BindingSyntax

protected

This enum type specifies the different syntaxes for specifying placeholders in prepared queries.

Constant	Value	Description
`QSqlResult::PositionalBinding`	`0`	Use the ODBC-style positional syntax, with "?" as placeholders.
`QSqlResult::NamedBinding`	`1`	Use the Oracle-style syntax with named placeholders (e.g., ":id")

See also: bindingSyntax()

Constructor & Destructor Documentation

QSqlResult::~QSqlResult ( )

virtual

Destroys the object and frees any allocated resources.

QSqlResult::QSqlResult ( const QSqlDriver * db )

explicitprotected

Creates a QSqlResult using the given database driver db. The object is initialized to an inactive state.

See also: isActive(), driver()

Method Documentation

void QSqlResult::addBindValue	(	const QVariant &	value,
		QSql::ParamType	type
	)

protected

Binds the value of parameter type to the next available position in the current record (row).

See also: bindValue()

int QSqlResult::at ( ) const

protected

Returns the current (zero-based) row position of the result. May return the special values QSql::BeforeFirstRow or QSql::AfterLastRow.

See also: setAt(), isValid()

BindingSyntax QSqlResult::bindingSyntax ( ) const

protected

Returns the binding syntax used by prepared queries.

void QSqlResult::bindValue	(	const QString &	placeholder,
		const QVariant &	value,
		QSql::ParamType	type
	)

protectedvirtual

Binds the value parameter type to the placeholder name in the current record (row). Values can not be bound to multiple locations in the query.

INSERT INTO testtable (id, name, samename) VALUES (:id, :name, :name)

Binding to name will bind to the first :name, but not the second.

Note: Binding an undefined placeholder will result in undefined behavior.

See also: QSqlQuery::bindValue()

void QSqlResult::bindValue	(	int	index,
		const QVariant &	value,
		QSql::ParamType	type
	)

protectedvirtual

Binds the value of parameter type to position index in the current record (row).

See also: addBindValue()

QSql::ParamType QSqlResult::bindValueType ( const QString & placeholder ) const

protected

Returns the parameter type for the value bound with the given placeholder name.

QSql::ParamType QSqlResult::bindValueType ( int index ) const

protected

Returns the parameter type for the value bound at position index.

See also: boundValue()

QVariant QSqlResult::boundValue ( const QString & placeholder ) const

protected

Returns the value bound by the given placeholder name in the current record (row).

See also: bindValueType()

QVariant QSqlResult::boundValue ( int index ) const

protected

Returns the value bound at position index in the current record (row).

See also: bindValue(), boundValues()

int QSqlResult::boundValueCount ( ) const

protected

Returns the number of bound values in the result.

See also: boundValues()

QString QSqlResult::boundValueName ( int index ) const

protected

Returns the name of the bound value at position index in the current record (row).

See also: boundValue()

QVector< QVariant > & QSqlResult::boundValues ( ) const

protected

Returns a vector of the result's bound values for the current record (row).

See also: boundValueCount()

void QSqlResult::clear ( )

protected

Clears the entire result set and releases any associated resources.

QVariant QSqlResult::data ( int index )

protectedpure virtual

Returns the data for field index in the current row as a QVariant. This method is only called if the result is in an active state and is positioned on a valid record and index is non-negative. Derived classes must reimplement this function and return the value of field index, or QVariant() if it can not be determined.

const QSqlDriver * QSqlResult::driver ( ) const

protected

Returns the driver associated with the result. This is the object that was passed to the constructor.

bool QSqlResult::exec ( )

protectedvirtual

Executes the query and returns true if successful, otherwise returns false.

See also: prepare()

QString QSqlResult::executedQuery ( ) const

protected

Returns the query that was actually executed. This may differ from the query that was passed, for example if bound values were used with a prepared query and the underlying database does not support prepared queries.

See also: exec(), setQuery()

bool QSqlResult::fetch ( int index )

protectedpure virtual

Positions the result to an arbitrary (zero-based) row index.

This function is only called if the result is in an active state. Derived classes must reimplement this function and position the result to the row index, and call setAt() with an appropriate value. Return true to indicate success, or false to signify failure.

See also: isActive(), fetchFirst(), fetchLast(), fetchNext(), fetchPrevious()

bool QSqlResult::fetchFirst ( )

protectedpure virtual

Positions the result to the first record (row 0) in the result.

This method is only called if the result is in an active state. Derived classes must reimplement this function and position the result to the first record, and call setAt() with an appropriate value. Return true to indicate success, or false to signify failure.

See also: fetch(), fetchLast()

bool QSqlResult::fetchLast ( )

protectedpure virtual

Positions the result to the last record (last row) in the result.

This function is only called if the result is in an active state. Derived classes must reimplement this function and position the result to the last record, and call setAt() with an appropriate value. Return true to indicate success, or false to signify failure.

See also: fetch(), fetchFirst()

bool QSqlResult::fetchNext ( )

protectedvirtual

Positions the result to the next available record (row) in the result.

This method is only called if the result is in an active state. The default implementation calls fetch() with the next index. Derived classes can reimplement this function and position the result to the next record in some other way, and call setAt() with an appropriate value. Return true to indicate success, or false to signify failure.

See also: fetch(), fetchPrevious()

bool QSqlResult::fetchPrevious ( )

protectedvirtual

Positions the result to the previous record (row) in the result.

This method is only called if the result is in an active state. The default implementation calls fetch() with the previous index. Derived classes can reimplement this function and position the result to the next record in some other way, and call setAt() with an appropriate value. Return true to indicate success, or false to signify failure.

QVariant QSqlResult::handle ( ) const

virtual

Returns the low-level database handle for this result set wrapped in a QVariant or an invalid QVariant if there is no handle. The handle returned here can become a stale pointer if the result is modified (for example, if you clear it). The handle can be NULL if the result was not executed yet. The handle returned here is database-dependent, you should query the type name of the variant before accessing it.

This example retrieves the handle for a sqlite result.

QSqlQuery query = ...
QVariant v = query.result()->handle();
 
if (v.isValid() && qstrcmp(v.typeName(), "sqlite3_stmt*")) {
    // v.data() returns a pointer to the handle
    sqlite3_stmt *handle = *static_cast<sqlite3_stmt **>(v.data());
 
    if (handle != 0) { // check that it is not NULL
        ...
    }
}

This example returns the handle for PostgreSQL or MySQL.

if (v.typeName() == "PGresult*") {
    PGresult *handle = *static_cast<PGresult **>(v.data());
    if (handle != 0) ...
}
 
if (v.typeName() == "MYSQL_STMT*") {
    MYSQL_STMT *handle = *static_cast<MYSQL_STMT **>(v.data());
    if (handle != 0) ...
}

See also: QSqlDriver::handle()

bool QSqlResult::hasOutValues ( ) const

protected

Returns true if at least one of the query's bound values is a QSql::Out or a QSql::InOut, otherwise returns false.

See also: bindValueType()

bool QSqlResult::isActive ( ) const

protected

Returns true if the result has records to be retrieved, otherwise returns false.

bool QSqlResult::isForwardOnly ( ) const

protected

Returns true if you can only scroll forward through the result set, otherwise returns false.

See also: setForwardOnly()

bool QSqlResult::isNull ( int index )

protectedpure virtual

Returns true if the field at position index in the current row is null, otherwise returns false.

bool QSqlResult::isSelect ( ) const

protected

Returns true if the current result is from a SELECT statement, otherwise returns false.

See also: setSelect()

bool QSqlResult::isValid ( ) const

protected

Returns true if the result is positioned on a valid record (that is, the result is not positioned before the first or after the last record), otherwise returns false.

See also: at()

QSqlError QSqlResult::lastError ( ) const

protected

Returns the last error associated with the result.

See also: setLastError()

QVariant QSqlResult::lastInsertId ( ) const

protectedvirtual

Returns the object ID of the most recent inserted row if the database supports it. An invalid QVariant will be returned if the query did not insert any value or if the database does not report the id back. If more than one row was touched by the insert, the behavior is undefined.

Note that for Oracle databases the row's ROWID will be returned, while for MySQL databases the row's auto-increment field will be returned.

See also: QSqlDriver::hasFeature()

QString QSqlResult::lastQuery ( ) const

protected

Returns the current SQL query text, or an empty string if there is not one.

See also: setQuery()

int QSqlResult::numRowsAffected ( )

protectedpure virtual

Returns the number of rows affected by the last query executed, or -1 if it can not be determined or if the query is a SELECT statement.

See also: size()

bool QSqlResult::prepare ( const QString & query )

protectedvirtual

Prepares the given query for execution. The query will normally use placeholders so that it can be executed repeatedly. Returns true if the query is prepared successfully, otherwise returns false.

See also: exec()

QSqlRecord QSqlResult::record ( ) const

protectedvirtual

Returns the current record if the query is active, otherwise returns an empty QSqlRecord.

The default implementation always returns an empty QSqlRecord.

See also: isActive()

bool QSqlResult::reset ( const QString & query )

protectedpure virtual

Sets the result to use the SQL statement query for subsequent data retrieval.

Derived classes must reimplement this method and apply the sqlquery to the database. This method is only called after the result is set to an inactive state and is positioned before the first record of the new result. Derived classes should return true if the query was successful and ready to be used, or false otherwise.

See also: setQuery()

bool QSqlResult::savePrepare ( const QString & query )

protectedvirtual

Prepares the given query, using the underlying database functionality where possible. Returns true if the query is prepared successfully, otherwise returns false.

See also: prepare()

void QSqlResult::setActive ( bool active )

protectedvirtual

This function is provided for derived classes to set the internal active state to active.

See also: isActive()

void QSqlResult::setAt ( int index )

protectedvirtual

This function is provided for derived classes to set the internal (zero-based) row position to index.

See also: at()

void QSqlResult::setForwardOnly ( bool forward )

protectedvirtual

Sets forward only mode to forward. If forward is true, only fetchNext() is allowed for navigating the results. Forward only mode needs much less memory since results do not have to be cached. By default, this feature is disabled. Setting forward only to false is a suggestion to the database engine, which has the final say on whether a result set is forward only or scrollable. isForwardOnly() will always return the correct status of the result set.

Note: Calling setForwardOnly() after execution of the query will result in unexpected results at best and may crash the program.

See also: isForwardOnly(), fetchNext(), QSqlQuery::setForwardOnly()

void QSqlResult::setLastError ( const QSqlError & error )

protectedvirtual

This method is provided for derived classes to set the last error to error.

See also: lastError()

void QSqlResult::setQuery ( const QString & query )

protectedvirtual

Sets the current query for the result to query. You must call reset() to execute the query on the database.

See also: reset(), lastQuery()

void QSqlResult::setSelect ( bool select )

protectedvirtual

This method is provided for derived classes to indicate whether or not the current statement is a SQL SELECT statement. The select parameter should be true if the statement is a SELECT statement, otherwise it should be false.

See also: isSelect()

int QSqlResult::size ( )

protectedpure virtual

Returns the size of the SELECT result, or -1 if it can not be determined or if the query is not a SELECT statement.

See also: numRowsAffected()

Public Methods

Protected Types

Protected Methods

Friends

Detailed Description

Member Enumeration Documentation

Constructor & Destructor Documentation

Method Documentation