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QSqlResult Class Reference
^{[QtSql module]}

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

Types

• enum BindingSyntax { PositionalBinding, NamedBinding }

Methods

• __init__ (self, QSqlDriver db)
• addBindValue (self, QVariant val, QSql.ParamType type)
• int at (self)
• BindingSyntax bindingSyntax (self)
• bindValue (self, int pos, QVariant val, QSql.ParamType type)
• bindValue (self, QString placeholder, QVariant val, QSql.ParamType type)
• QSql.ParamType bindValueType (self, QString placeholder)
• QSql.ParamType bindValueType (self, int pos)
• QVariant boundValue (self, QString placeholder)
• QVariant boundValue (self, int pos)
• int boundValueCount (self)
• QString boundValueName (self, int pos)
• list-of-QVariant boundValues (self)
• clear (self)
• QVariant data (self, int i)
• QSqlDriver driver (self)
• bool exec_ (self)
• QString executedQuery (self)
• bool fetch (self, int i)
• bool fetchFirst (self)
• bool fetchLast (self)
• bool fetchNext (self)
• bool fetchPrevious (self)
• QVariant handle (self)
• bool hasOutValues (self)
• bool isActive (self)
• bool isForwardOnly (self)
• bool isNull (self, int i)
• bool isSelect (self)
• bool isValid (self)
• QSqlError lastError (self)
• QVariant lastInsertId (self)
• QString lastQuery (self)
• int numRowsAffected (self)
• bool prepare (self, QString query)
• QSqlRecord record (self)
• bool reset (self, QString sqlquery)
• bool savePrepare (self, QString sqlquery)
• setActive (self, bool a)
• setAt (self, int at)
• setForwardOnly (self, bool forward)
• setLastError (self, QSqlError e)
• setQuery (self, QString query)
• setSelect (self, bool s)
• int size (self)

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.

Type Documentation

QSqlResult.BindingSyntax

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

See also bindingSyntax().

Method Documentation

QSqlResult.__init__ (self, QSqlDriver db)

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

See also isActive() and driver().

QSqlResult.addBindValue (self, QVariant val, QSql.ParamType type)

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

See also bindValue().

int QSqlResult.at (self)

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

See also setAt() and isValid().

BindingSyntax QSqlResult.bindingSyntax (self)

Returns the binding syntax used by prepared queries.

QSqlResult.bindValue (self, int pos, QVariant val, QSql.ParamType type)

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

See also addBindValue().

QSqlResult.bindValue (self, QString placeholder, QVariant val, QSql.ParamType type)

This is an overloaded function.

Binds the value val of parameter type paramType to the placeholder name in the current record (row).

Values cannot be bound to multiple locations in the query, eg:

 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().

QSql.ParamType QSqlResult.bindValueType (self, QString placeholder)

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

See also boundValue().

QSql.ParamType QSqlResult.bindValueType (self, int pos)

This is an overloaded function.

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

QVariant QSqlResult.boundValue (self, QString placeholder)

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

See also bindValue() and boundValues().

QVariant QSqlResult.boundValue (self, int pos)

This is an overloaded function.

See also bindValueType().

int QSqlResult.boundValueCount (self)

Returns the number of bound values in the result.

See also boundValues().

QString QSqlResult.boundValueName (self, int pos)

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

See also boundValue().

list-of-QVariant QSqlResult.boundValues (self)

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

See also boundValueCount().

QSqlResult.clear (self)

Clears the entire result set and releases any associated resources.

QVariant QSqlResult.data (self, int i)

This method is abstract and should be reimplemented in any sub-class.

Returns the data for field index in the current row as a QVariant. This function 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 cannot be determined.

QSqlDriver QSqlResult.driver (self)

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

bool QSqlResult.exec_ (self)

Executes the query, returning true if successful; otherwise returns false.

See also prepare().

QString QSqlResult.executedQuery (self)

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 doesn't support prepared queries.

See also exec_() and setQuery().

bool QSqlResult.fetch (self, int i)

This method is abstract and should be reimplemented in any sub-class.

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(), and fetchPrevious().

bool QSqlResult.fetchFirst (self)

This method is abstract and should be reimplemented in any sub-class.

Positions the result to the first record (row 0) 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 first record, and call setAt() with an appropriate value. Return true to indicate success, or false to signify failure.

See also fetch() and fetchLast().

bool QSqlResult.fetchLast (self)

This method is abstract and should be reimplemented in any sub-class.

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() and fetchFirst().

bool QSqlResult.fetchNext (self)

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

This function 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() and fetchPrevious().

bool QSqlResult.fetchPrevious (self)

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

This function 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 (self)

Returns the low-level database handle for this result set wrapped in a QVariant or an invalid QVariant if there is no handle.

Warning: Use this with uttermost care and only if you know what you're doing.

Warning: The handle returned here can become a stale pointer if the result is modified (for example, if you clear it).

Warning: 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 snippet 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 (self)

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 (self)

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

bool QSqlResult.isForwardOnly (self)

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

See also setForwardOnly().

bool QSqlResult.isNull (self, int i)

This method is abstract and should be reimplemented in any sub-class.

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

bool QSqlResult.isSelect (self)

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

See also setSelect().

bool QSqlResult.isValid (self)

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 (self)

Returns the last error associated with the result.

See also setLastError().

QVariant QSqlResult.lastInsertId (self)

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 (self)

Returns the current SQL query text, or an empty string if there isn't one.

See also setQuery().

int QSqlResult.numRowsAffected (self)

This method is abstract and should be reimplemented in any sub-class.

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

See also size().

bool QSqlResult.prepare (self, QString query)

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 (self)

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 (self, QString sqlquery)

This method is abstract and should be reimplemented in any sub-class.

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

See also setQuery().

bool QSqlResult.savePrepare (self, QString sqlquery)

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().

QSqlResult.setActive (self, bool a)

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

See also isActive().

QSqlResult.setAt (self, int at)

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

See also at().

QSqlResult.setForwardOnly (self, bool forward)

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 crashes at worst.

See also isForwardOnly(), fetchNext(), and QSqlQuery.setForwardOnly().

QSqlResult.setLastError (self, QSqlError e)

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

See also lastError().

QSqlResult.setQuery (self, QString query)

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

See also reset() and lastQuery().

QSqlResult.setSelect (self, bool s)

This function 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 (self)

This method is abstract and should be reimplemented in any sub-class.

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

See also numRowsAffected().