--- name: "qsqldriver" section: "3qt" platform: "linux" package: "qt3-doc" version: "3:3.3.8b-7" release: "Debian 6.0 (Squeeze)" platforms: ["linux"] url: "https://new.carta.tech/qsqldriver" --- # qsqldriver(3qt) Abstract base class for accessing SQL databases ## NAME QSqlDriver - Abstract base class for accessing SQL databases ## SYNOPSIS `#include ` Inherits QObject. ### Public Members **enum DriverFeature { Transactions, QuerySize, BLOB, Unicode, PreparedQueries, NamedPlaceholders, PositionalPlaceholders }**\ **QSqlDriver ( QObject \* parent = 0, const char \* name = 0 )**\ **~QSqlDriver ()**\ **bool isOpen () const**\ **bool isOpenError () const**\ **virtual bool beginTransaction ()**\ **virtual bool commitTransaction ()**\ **virtual bool rollbackTransaction ()**\ **virtual QStringList tables ( const QString & tableType ) const**\ **virtual QSqlIndex primaryIndex ( const QString & tableName ) const**\ **virtual QSqlRecord record ( const QString & tableName ) const**\ **virtual QSqlRecord record ( const QSqlQuery & query ) const**\ **virtual QSqlRecordInfo recordInfo ( const QString & tablename ) const**\ **virtual QSqlRecordInfo recordInfo ( const QSqlQuery & query ) const**\ **virtual QString nullText () const**\ **virtual QString formatValue ( const QSqlField \* field, bool trimStrings = FALSE ) const**\ **QSqlError lastError () const**\ **virtual bool hasFeature ( DriverFeature f ) const = 0**\ **virtual bool open ( const QString & db, const QString & user = QString::null, const QString & password = QString::null, const QString & host = QString::null, int port = -1 ) = 0**\ **virtual void close () = 0**\ **virtual QSqlQuery createQuery () const = 0**\ **bool open ( const QString & db, const QString & user, const QString & password, const QString & host, int port, const QString & connOpts )**\ ### Protected Members **virtual void setOpen ( bool o )**\ **virtual void setOpenError ( bool e )**\ **virtual void setLastError ( const QSqlError & e )**\ ## DESCRIPTION The QSqlDriver class is an abstract base class for accessing SQL databases. This class should not be used directly. Use QSqlDatabase instead. See also Database Classes. ### Member Type Documentation ## QSqlDriver::DriverFeature This enum contains a list of features a driver may support. Use hasFeature() to query whether a feature is supported or not. - `QSqlDriver::Transactions` - whether the driver supports SQL transactions - `QSqlDriver::QuerySize` - whether the database is capable of reporting the size of a query. Note that some databases do not support returning the size (i.e. number of rows returned) of a query, in which case QSqlQuery::size() will return -1 - `QSqlDriver::BLOB` - whether the driver supports Binary Large Object fields - `QSqlDriver::Unicode` - whether the driver supports Unicode strings if the database server does - `QSqlDriver::PreparedQueries` - whether the driver supports prepared query execution - `QSqlDriver::NamedPlaceholders` - whether the driver supports usage of named placeholders - `QSqlDriver::PositionalPlaceholders` - whether the driver supports usage of positional placeholders More information about supported features can be found in the Qt SQL driver documentation. See also hasFeature(). ## MEMBER FUNCTION DOCUMENTATION ## QSqlDriver::QSqlDriver ( QObject \* parent = 0, const char \* name = 0 ) Default constructor. Creates a new driver with parent *parent*, called *name*. ## QSqlDriver::~QSqlDriver () Destroys the object and frees any allocated resources. ## bool QSqlDriver::beginTransaction ()` [virtual]` Protected function which derived classes can reimplement to begin a transaction. If successful, return TRUE, otherwise return FALSE. The default implementation returns FALSE. See also commitTransaction() and rollbackTransaction(). ## void QSqlDriver::close ()` [pure virtual]` Derived classes must reimplement this abstract virtual function in order to close the database connection. Return TRUE on success, FALSE on failure. See also setOpen(). ## bool QSqlDriver::commitTransaction ()` [virtual]` Protected function which derived classes can reimplement to commit a transaction. If successful, return TRUE, otherwise return FALSE. The default implementation returns FALSE. See also beginTransaction() and rollbackTransaction(). ## QSqlQuery QSqlDriver::createQuery () const` [pure virtual]` Creates an empty SQL result on the database. Derived classes must reimplement this function and return a QSqlQuery object appropriate for their database to the caller. ## QString QSqlDriver::formatValue ( const QSqlField \* field, bool trimStrings = FALSE ) const` [virtual]` Returns a string representation of the *field* value for the database. This is used, for example, when constructing INSERT and UPDATE statements. The default implementation returns the value formatted as a string according to the following rules: - - If *field* is NULL, nullText() is returned. - - If *field* is character data, the value is returned enclosed in single quotation marks, which is appropriate for many SQL databases. Any embedded single-quote characters are escaped (replaced with two single-quote characters). If *trimStrings* is TRUE (the default is FALSE), all trailing whitespace is trimmed from the field. - - If *field* is date/time data, the value is formatted in ISO format and enclosed in single quotation marks. If the date/time data is invalid, nullText() is returned. - - If *field* is bytearray data, and the driver can edit binary fields, the value is formatted as a hexadecimal string. - - For any other field type toString() will be called on its value and the result returned. - See also QVariant::toString(). ## bool QSqlDriver::hasFeature ( DriverFeature f ) const` [pure virtual]` Returns TRUE if the driver supports feature *f*; otherwise returns FALSE. Note that some databases need to be open() before this can be determined. See also DriverFeature. ## bool QSqlDriver::isOpen () const Returns TRUE if the database connection is open; otherwise returns FALSE. ## bool QSqlDriver::isOpenError () const Returns TRUE if the there was an error opening the database connection; otherwise returns FALSE. ## QSqlError QSqlDriver::lastError () const Returns a QSqlError object which contains information about the last error that occurred on the database. ## QString QSqlDriver::nullText () const` [virtual]` Returns a string representation of the NULL value for the database. This is used, for example, when constructing INSERT and UPDATE statements. The default implementation returns the string" NULL". ## bool QSqlDriver::open ( const QString & db, const QString & user = QString::null, const QString & password = QString::null, const QString & host = QString::null, int port = -1 )` [pure virtual]` Derived classes must reimplement this abstract virtual function in order to open a database connection on database *db*, using user name *user*, password *password*, host *host* and port *port*. The function *must* return TRUE on success and FALSE on failure. See also setOpen(). ## bool QSqlDriver::open ( const QString & db, const QString & user, const QString & password, const QString & host, int port, const QString & connOpts ) This is an overloaded member function, provided for convenience. It behaves essentially like the above function. Open a database connection on database *db*, using user name *user*, password *password*, host *host*, port *port* and connection options *connOpts*. Returns TRUE on success and FALSE on failure. See also setOpen(). ## QSqlIndex QSqlDriver::primaryIndex ( const QString & tableName ) const` [virtual]` Returns the primary index for table *tableName*. Returns an empty QSqlIndex if the table doesn't have a primary index. The default implementation returns an empty index. ## QSqlRecord QSqlDriver::record ( const QString & tableName ) const` [virtual]` Returns a QSqlRecord populated with the names of the fields in table *tableName*. If no such table exists, an empty record is returned. The default implementation returns an empty record. ## QSqlRecord QSqlDriver::record ( const QSqlQuery & query ) const` [virtual]` This is an overloaded member function, provided for convenience. It behaves essentially like the above function. Returns a QSqlRecord populated with the names of the fields in the SQL *query*. The default implementation returns an empty record. ## QSqlRecordInfo QSqlDriver::recordInfo ( const QString & tablename ) const` [virtual]` Returns a QSqlRecordInfo object with meta data about the table *tablename*. ## QSqlRecordInfo QSqlDriver::recordInfo ( const QSqlQuery & query ) const` [virtual]` This is an overloaded member function, provided for convenience. It behaves essentially like the above function. Returns a QSqlRecordInfo object with meta data for the QSqlQuery *query*. Note that this overloaded function may return less information than the recordInfo() function which takes the name of a table as parameter. ## bool QSqlDriver::rollbackTransaction ()` [virtual]` Protected function which derived classes can reimplement to rollback a transaction. If successful, return TRUE, otherwise return FALSE. The default implementation returns FALSE. See also beginTransaction() and commitTransaction(). ## void QSqlDriver::setLastError ( const QSqlError & e )` [virtual protected]` Protected function which allows derived classes to set the value of the last error, *e*, that occurred on the database. See also lastError(). ## void QSqlDriver::setOpen ( bool o )` [virtual protected]` Protected function which sets the open state of the database to *o*. Derived classes can use this function to report the status of open(). See also open() and setOpenError(). ## void QSqlDriver::setOpenError ( bool e )` [virtual protected]` Protected function which sets the open error state of the database to *e*. Derived classes can use this function to report the status of open(). Note that if *e* is TRUE the open state of the database is set to closed (i.e. isOpen() returns FALSE). See also open(). ## QStringList QSqlDriver::tables ( const QString & tableType ) const` [virtual]` Returns a list of tables in the database. The default implementation returns an empty list. The *tableType* argument describes what types of tables should be returned. Due to binary compatibility, the string contains the value of the enum QSql::TableTypes as text. An empty string should be treated as QSql::Tables for downward compatibility. See also QSql::TableType. ## SEE ALSO **http://doc.trolltech.com/qsqldriver.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 (qsqldriver.3qt) and the Qt version (3.3.8).