CopperSpice API  1.7.2
QSqlResult Class Referenceabstract

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

Inherited by QSqlCachedResult, and 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 QSqlDriverdriver () 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 specific 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 subclassing QSqlDriver), you will need to provide your own QSqlResult subclass that implements all the pure virtual functions and other virtual functions 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.

ConstantValueDescription
QSqlResult::PositionalBinding0 Use the ODBC-style positional syntax, with "?" as placeholders.
QSqlResult::NamedBinding1 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()