qsqldatabase.cpp « kernel « sql « src - qt/qtbase.git - Qt Base (Core, Gui, Widgets, Network, ...)

path: root / src / sql / kernel / qsqldatabase.cpp

blob: 4a966dcfa7c8fea89d75710e8c9ed648349fbc1c ( plain ) // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only #include "qsqldatabase.h" #include "qsqlquery.h" #include "qdebug.h" #include "qcoreapplication.h" #include "qreadwritelock.h" #include "qsqldriver.h" #include "qsqldriverplugin.h" #include "qsqlindex.h" #include "QtCore/qapplicationstatic.h" #include "private/qfactoryloader_p.h" #include "private/qsqlnulldriver_p.h" #include "qhash.h" #include "qthread.h" QT_BEGIN_NAMESPACE using namespace Qt :: StringLiterals ; Q_GLOBAL_STATIC_WITH_ARGS ( QFactoryLoader , loader , ( QSqlDriverFactoryInterface_iid , "/sqldrivers" _L1 )) const char * QSqlDatabase :: defaultConnection = "qt_sql_default_connection" ; class QConnectionDict : public QHash < QString , QSqlDatabase > public : QSqlDatabase value_ts ( const QString & key ) const QReadLocker locker (& lock ); return value ( key ); bool contains_ts ( const QString & key ) const QReadLocker locker (& lock ); return contains ( key ); QStringList keys_ts () const QReadLocker locker (& lock ); return keys (); mutable QReadWriteLock lock ; Q_GLOBAL_STATIC ( QConnectionDict , dbDict ) namespace { struct DriverDict : public QHash < QString , QSqlDriverCreatorBase *> ~ DriverDict (); Q_APPLICATION_STATIC ( DriverDict , qtDriverDict ) class QSqlDatabasePrivate public : QSqlDatabasePrivate ( QSqlDriver * dr ): ref ( 1 ), driver ( dr ), port (- 1 ) precisionPolicy = QSql :: LowPrecisionDouble ; QSqlDatabasePrivate ( const QSqlDatabasePrivate & other ); ~ QSqlDatabasePrivate (); void init ( const QString & type ); void copy ( const QSqlDatabasePrivate * other ); void disable (); QAtomicInt ref ; QSqlDriver * driver ; QString dbname ; QString uname ; QString pword ; QString hname ; QString drvName ; int port ; QString connOptions ; QString connName ; QSql :: NumericalPrecisionPolicy precisionPolicy ; static QSqlDatabasePrivate * shared_null (); static QSqlDatabase database ( const QString & name , bool open ); static void addDatabase ( const QSqlDatabase & db , const QString & name ); static void removeDatabase ( const QString & name ); static void invalidateDb ( const QSqlDatabase & db , const QString & name , bool doWarn = true ); static DriverDict & driverDict (); static void cleanConnections (); QSqlDatabasePrivate :: QSqlDatabasePrivate ( const QSqlDatabasePrivate & other ) : ref ( 1 ) dbname = other . dbname ; uname = other . uname ; pword = other . pword ; hname = other . hname ; drvName = other . drvName ; port = other . port ; connOptions = other . connOptions ; driver = other . driver ; precisionPolicy = other . precisionPolicy ; if ( driver ) driver -> setNumericalPrecisionPolicy ( other . driver -> numericalPrecisionPolicy ()); QSqlDatabasePrivate ::~ QSqlDatabasePrivate () if ( driver != shared_null ()-> driver ) delete driver ; void QSqlDatabasePrivate :: cleanConnections () QConnectionDict * dict = dbDict (); Q_ASSERT ( dict ); QWriteLocker locker (& dict -> lock ); QConnectionDict :: iterator it = dict -> begin (); while ( it != dict -> end ()) { invalidateDb ( it . value (), it . key (), false ); ++ it ; dict -> clear (); DriverDict ::~ DriverDict () qDeleteAll (* this ); QSqlDatabasePrivate :: cleanConnections (); DriverDict & QSqlDatabasePrivate :: driverDict () return * qtDriverDict (); QSqlDatabasePrivate * QSqlDatabasePrivate :: shared_null () static QSqlNullDriver dr ; static QSqlDatabasePrivate n (& dr ); return & n ; void QSqlDatabasePrivate :: invalidateDb ( const QSqlDatabase & db , const QString & name , bool doWarn ) if ( db . d -> ref . loadRelaxed () != 1 && doWarn ) { qWarning ( "QSqlDatabasePrivate::removeDatabase: connection '%s' is still in use, " "all queries will cease to work." , name . toLocal8Bit (). constData ()); db . d -> disable (); db . d -> connName . clear (); void QSqlDatabasePrivate :: removeDatabase ( const QString & name ) QConnectionDict * dict = dbDict (); Q_ASSERT ( dict ); QWriteLocker locker (& dict -> lock ); if (! dict -> contains ( name )) return ; invalidateDb ( dict -> take ( name ), name ); void QSqlDatabasePrivate :: addDatabase ( const QSqlDatabase & db , const QString & name ) QConnectionDict * dict = dbDict (); Q_ASSERT ( dict ); QWriteLocker locker (& dict -> lock ); if ( dict -> contains ( name )) { invalidateDb ( dict -> take ( name ), name ); qWarning ( "QSqlDatabasePrivate::addDatabase: duplicate connection name '%s', old " "connection removed." , name . toLocal8Bit (). data ()); dict -> insert ( name , db ); db . d -> connName = name ; /*! \internal QSqlDatabase QSqlDatabasePrivate :: database ( const QString & name , bool open ) const QConnectionDict * dict = dbDict (); Q_ASSERT ( dict ); QSqlDatabase db = dict -> value_ts ( name ); if (! db . isValid ()) return db ; if ( db . driver ()-> thread () != QThread :: currentThread ()) { qWarning ( "QSqlDatabasePrivate::database: requested database does not belong to the calling thread." ); return QSqlDatabase (); if ( open && ! db . isOpen ()) { if (! db . open ()) qWarning () << "QSqlDatabasePrivate::database: unable to open database:" << db . lastError (). text (); return db ; /*! \internal Copies the connection data from \a other. void QSqlDatabasePrivate :: copy ( const QSqlDatabasePrivate * other ) dbname = other -> dbname ; uname = other -> uname ; pword = other -> pword ; hname = other -> hname ; drvName = other -> drvName ; port = other -> port ; connOptions = other -> connOptions ; precisionPolicy = other -> precisionPolicy ; if ( driver ) driver -> setNumericalPrecisionPolicy ( other -> driver -> numericalPrecisionPolicy ()); void QSqlDatabasePrivate :: disable () if ( driver != shared_null ()-> driver ) { delete driver ; driver = shared_null ()-> driver ; \class QSqlDriverCreatorBase \brief The QSqlDriverCreatorBase class is the base class for SQL driver factories. \ingroup database \inmodule QtSql Reimplement createObject() to return an instance of the specific QSqlDriver subclass that you want to provide. See QSqlDatabase::registerSqlDriver() for details. \sa QSqlDriverCreator \fn QSqlDriverCreatorBase::~QSqlDriverCreatorBase() Destroys the SQL driver creator object. \fn QSqlDriver *QSqlDriverCreatorBase::createObject() const Reimplement this function to returns a new instance of a QSqlDriver subclass. \class QSqlDriverCreator \brief The QSqlDriverCreator class is a template class that provides a SQL driver factory for a specific driver type. \ingroup database \inmodule QtSql QSqlDriverCreator<T> instantiates objects of type T, where T is a QSqlDriver subclass. See QSqlDatabase::registerSqlDriver() for details. \fn template <class T> QSqlDriver *QSqlDriverCreator<T>::createObject() const \reimp \class QSqlDatabase \brief The QSqlDatabase class handles a connection to a database. \ingroup database \inmodule QtSql The QSqlDatabase class provides an interface for accessing a database through a connection. An instance of QSqlDatabase represents the connection. The connection provides access to the database via one of the \l{SQL Database Drivers#Supported Databases} {supported database drivers}, which are derived from QSqlDriver. Alternatively, you can subclass your own database driver from QSqlDriver. See \l{How to Write Your Own Database Driver} for more information. Create a connection (i.e., an instance of QSqlDatabase) by calling one of the static addDatabase() functions, where you specify \l{SQL Database Drivers#Supported Databases} {the driver or type of driver} to use (depending on the type of database) and a connection name. A connection is known by its own name, \e{not} by the name of the database it connects to. You can have multiple connections to one database. QSqlDatabase also supports the concept of a \e{default} connection, which is the unnamed connection. To create the default connection, don't pass the connection name argument when you call addDatabase(). Subsequently, the default connection will be assumed if you call any static member function without specifying the connection name. The following snippet shows how to create and open a default connection to a PostgreSQL database: \snippet sqldatabase/sqldatabase.cpp 0 Once the QSqlDatabase object has been created, set the connection parameters with setDatabaseName(), setUserName(), setPassword(), setHostName(), setPort(), and setConnectOptions(). Then call open() to activate the physical connection to the database. The connection is not usable until you open it. The connection defined above will be the \e{default} connection, because we didn't give a connection name to \l{QSqlDatabase::} {addDatabase()}. Subsequently, you can get the default connection by calling database() without the connection name argument: \snippet sqldatabase/sqldatabase.cpp 1 QSqlDatabase is a value class. Changes made to a database connection via one instance of QSqlDatabase will affect other instances of QSqlDatabase that represent the same connection. Use cloneDatabase() to create an independent database connection based on an existing one. \warning It is highly recommended that you do not keep a copy of the QSqlDatabase around as a member of a class, as this will prevent the instance from being correctly cleaned up on shutdown. If you need to access an existing QSqlDatabase, it should be accessed with database(). If you chose to have a QSqlDatabase member variable, this needs to be deleted before the QCoreApplication instance is deleted, otherwise it may lead to undefined behavior. If you create multiple database connections, specify a unique connection name for each one, when you call addDatabase(). Use database() with a connection name to get that connection. Use removeDatabase() with a connection name to remove a connection. QSqlDatabase outputs a warning if you try to remove a connection referenced by other QSqlDatabase objects. Use contains() to see if a given connection name is in the list of connections. \table \header \li {2,1}Some utility methods: \li tables() \li returns the list of tables \li primaryIndex() \li returns a table's primary index \li record() \li returns meta-information about a table's fields \li transaction() \li starts a transaction \li commit() \li saves and completes a transaction \li rollback() \li cancels a transaction \li hasFeature() \li checks if a driver supports transactions \li lastError() \li returns information about the last error \li drivers() \li returns the names of the available SQL drivers \li isDriverAvailable() \li checks if a particular driver is available \li registerSqlDriver() \li registers a custom-made driver \endtable \note When using transactions, you must start the transaction before you create your query. \sa QSqlDriver, QSqlQuery, {Qt SQL}, {Threads and the SQL Module} /*! \fn QSqlDatabase QSqlDatabase::addDatabase(const QString &type, const QString &connectionName) \threadsafe Adds a database to the list of database connections using the driver \a type and the connection name \a connectionName. If there already exists a database connection called \a connectionName, that connection is removed. The database connection is referred to by \a connectionName. The newly added database connection is returned. If \a type is not available or could not be loaded, isValid() returns \c false. If \a connectionName is not specified, the new connection becomes the default connection for the application, and subsequent calls to database() without the connection name argument will return the default connection. If a \a connectionName is provided here, use database(\a connectionName) to retrieve the connection. \warning If you add a connection with the same name as an existing connection, the new connection replaces the old one. If you call this function more than once without specifying \a connectionName, the default connection will be the one replaced. Before using the connection, it must be initialized. e.g., call some or all of setDatabaseName(), setUserName(), setPassword(), setHostName(), setPort(), and setConnectOptions(), and, finally, open(). \sa database(), removeDatabase(), {Threads and the SQL Module} QSqlDatabase QSqlDatabase :: addDatabase ( const QString & type , const QString & connectionName ) QSqlDatabase db ( type ); QSqlDatabasePrivate :: addDatabase ( db , connectionName ); return db ; \threadsafe Returns the database connection called \a connectionName. The database connection must have been previously added with addDatabase(). If \a open is true (the default) and the database connection is not already open it is opened now. If no \a connectionName is specified the default connection is used. If \a connectionName does not exist in the list of databases, an invalid connection is returned. \sa isOpen(), {Threads and the SQL Module} QSqlDatabase QSqlDatabase :: database ( const QString & connectionName , bool open ) return QSqlDatabasePrivate :: database ( connectionName , open ); \threadsafe Removes the database connection \a connectionName from the list of database connections. \warning There should be no open queries on the database connection when this function is called, otherwise a resource leak will occur. Example: \snippet code/src_sql_kernel_qsqldatabase.cpp 0 The correct way to do it: \snippet code/src_sql_kernel_qsqldatabase.cpp 1 To remove the default connection, which may have been created with a call to addDatabase() not specifying a connection name, you can retrieve the default connection name by calling connectionName() on the database returned by database(). Note that if a default database hasn't been created an invalid database will be returned. \sa database(), connectionName(), {Threads and the SQL Module} void QSqlDatabase :: removeDatabase ( const QString & connectionName ) QSqlDatabasePrivate :: removeDatabase ( connectionName ); Returns a list of all the available database drivers. \sa registerSqlDriver() QStringList QSqlDatabase :: drivers () QStringList list ; if ( QFactoryLoader * fl = loader ()) { typedef QMultiMap < int , QString > PluginKeyMap ; const PluginKeyMap keyMap = fl -> keyMap (); for ( const QString & val : keyMap ) { if (! list . contains ( val )) list << val ; QReadLocker locker (& dbDict ()-> lock ); const DriverDict & dict = QSqlDatabasePrivate :: driverDict (); for ( const auto &[ k , _ ] : dict . asKeyValueRange ()) { if (! list . contains ( k )) list << k ; return list ; This function registers a new SQL driver called \a name, within the SQL framework. This is useful if you have a custom SQL driver and don't want to compile it as a plugin. Example: \snippet code/src_sql_kernel_qsqldatabase_snippet.cpp 2 QSqlDatabase takes ownership of the \a creator pointer, so you mustn't delete it yourself. \sa drivers() void QSqlDatabase :: registerSqlDriver ( const QString & name , QSqlDriverCreatorBase * creator ) QWriteLocker locker (& dbDict ()-> lock ); delete QSqlDatabasePrivate :: driverDict (). take ( name ); if ( creator ) QSqlDatabasePrivate :: driverDict (). insert ( name , creator ); \threadsafe Returns \c true if the list of database connections contains \a connectionName; otherwise returns \c false. \sa connectionNames(), database(), {Threads and the SQL Module} bool QSqlDatabase :: contains ( const QString & connectionName ) return dbDict ()-> contains_ts ( connectionName ); \threadsafe Returns a list containing the names of all connections. \sa contains(), database(), {Threads and the SQL Module} QStringList QSqlDatabase :: connectionNames () return dbDict ()-> keys_ts (); \overload Creates a QSqlDatabase connection that uses the driver referred to by \a type. If the \a type is not recognized, the database connection will have no functionality. The currently available driver types are: \table \header \li Driver Type \li Description \row \li QDB2 \li IBM DB2 \row \li QIBASE \li Borland InterBase Driver \row \li QMYSQL \li MySQL Driver \row \li QOCI \li Oracle Call Interface Driver \row \li QODBC \li ODBC Driver (includes Microsoft SQL Server) \row \li QPSQL \li PostgreSQL Driver \row \li QSQLITE \li SQLite version 3 or above \row \li QMIMER \li Mimer SQL 11 or above \endtable Additional third party drivers, including your own custom drivers, can be loaded dynamically. \sa {SQL Database Drivers}, registerSqlDriver(), drivers() QSqlDatabase :: QSqlDatabase ( const QString & type ) : d ( new QSqlDatabasePrivate ( nullptr )) d -> init ( type ); \overload Creates a database connection using the given \a driver. QSqlDatabase :: QSqlDatabase ( QSqlDriver * driver ) : d ( new QSqlDatabasePrivate ( driver )) Creates an empty, invalid QSqlDatabase object. Use addDatabase(), removeDatabase(), and database() to get valid QSqlDatabase objects. QSqlDatabase :: QSqlDatabase () : d ( QSqlDatabasePrivate :: shared_null ()) d -> ref . ref (); Creates a copy of \a other. QSqlDatabase :: QSqlDatabase ( const QSqlDatabase & other ) d = other . d ; d -> ref . ref (); Assigns \a other to this object. QSqlDatabase & QSqlDatabase :: operator =( const QSqlDatabase & other ) qAtomicAssign ( d , other . d ); return * this ; \internal Create the actual driver instance \a type. void QSqlDatabasePrivate :: init ( const QString & type ) drvName = type ; if (! driver ) { QReadLocker locker (& dbDict ()-> lock ); const DriverDict & dict = QSqlDatabasePrivate :: driverDict (); for ( DriverDict :: const_iterator it = dict . constBegin (); it != dict . constEnd () && ! driver ; ++ it ) { if ( type == it . key ()) { driver = (( QSqlDriverCreatorBase *)(* it ))-> createObject (); if (! driver && loader ()) driver = qLoadPlugin < QSqlDriver , QSqlDriverPlugin >( loader (), type ); if (! driver ) { qWarning ( "QSqlDatabase: %s driver not loaded" , type . toLatin1 (). data ()); qWarning ( "QSqlDatabase: available drivers: %s" , QSqlDatabase :: drivers (). join ( u ' ' ). toLatin1 (). data ()); if ( QCoreApplication :: instance () == nullptr ) qWarning ( "QSqlDatabase: an instance of QCoreApplication is required for loading driver plugins" ); driver = shared_null ()-> driver ; Destroys the object and frees any allocated resources. \note When the last connection is destroyed, the destructor implicitly calls close() to release the database connection. \sa close() QSqlDatabase ::~ QSqlDatabase () if (! d -> ref . deref ()) { close (); delete d ; Executes a SQL statement on the database and returns a QSqlQuery object. Use lastError() to retrieve error information. If \a query is empty, an empty, invalid query is returned and lastError() is not affected. \sa QSqlQuery, lastError() \deprecated [6.6] Use QSqlQuery::exec() instead. #if QT_DEPRECATED_SINCE(6, 6) QSqlQuery QSqlDatabase :: exec ( const QString & query ) const QSqlQuery r ( d -> driver -> createResult ()); if (! query . isEmpty ()) { r . exec ( query ); d -> driver -> setLastError ( r . lastError ()); return r ; #endif Opens the database connection using the current connection values. Returns \c true on success; otherwise returns \c false. Error information can be retrieved using lastError(). \sa lastError(), setDatabaseName(), setUserName(), setPassword(), setHostName(), setPort(), setConnectOptions() bool QSqlDatabase :: open () return d -> driver -> open ( d -> dbname , d -> uname , d -> pword , d -> hname , d -> port , d -> connOptions ); \overload Opens the database connection using the given \a user name and \a password. Returns \c true on success; otherwise returns \c false. Error information can be retrieved using the lastError() function. This function does not store the password it is given. Instead, the password is passed directly to the driver for opening the connection and it is then discarded. \sa lastError() bool QSqlDatabase :: open ( const QString & user , const QString & password ) setUserName ( user ); return d -> driver -> open ( d -> dbname , user , password , d -> hname , d -> port , d -> connOptions ); Closes the database connection, freeing any resources acquired, and invalidating any existing QSqlQuery objects that are used with the database. This will also affect copies of this QSqlDatabase object. \sa removeDatabase() void QSqlDatabase :: close () d -> driver -> close (); Returns \c true if the database connection is currently open; otherwise returns \c false. bool QSqlDatabase :: isOpen () const return d -> driver -> isOpen (); Returns \c true if there was an error opening the database connection; otherwise returns \c false. Error information can be retrieved using the lastError() function. bool QSqlDatabase :: isOpenError () const return d -> driver -> isOpenError (); Begins a transaction on the database if the driver supports transactions. Returns \c{true} if the operation succeeded. Otherwise it returns \c{false}. \sa QSqlDriver::hasFeature(), commit(), rollback() bool QSqlDatabase :: transaction () if (! d -> driver -> hasFeature ( QSqlDriver :: Transactions )) return false ; return d -> driver -> beginTransaction (); Commits a transaction to the database if the driver supports transactions and a transaction() has been started. Returns \c{true} if the operation succeeded. Otherwise it returns \c{false}. \note For some databases, the commit will fail and return \c{false} if there is an \l{QSqlQuery::isActive()} {active query} using the database for a \c{SELECT}. Make the query \l{QSqlQuery::isActive()} {inactive} before doing the commit. Call lastError() to get information about errors. \sa QSqlQuery::isActive(), QSqlDriver::hasFeature(), rollback() bool QSqlDatabase :: commit () if (! d -> driver -> hasFeature ( QSqlDriver :: Transactions )) return false ; return d -> driver -> commitTransaction (); Rolls back a transaction on the database, if the driver supports transactions and a transaction() has been started. Returns \c{true} if the operation succeeded. Otherwise it returns \c{false}. \note For some databases, the rollback will fail and return \c{false} if there is an \l{QSqlQuery::isActive()} {active query} using the database for a \c{SELECT}. Make the query \l{QSqlQuery::isActive()} {inactive} before doing the rollback. Call lastError() to get information about errors. \sa QSqlQuery::isActive(), QSqlDriver::hasFeature(), commit() bool QSqlDatabase :: rollback () if (! d -> driver -> hasFeature ( QSqlDriver :: Transactions )) return false ; return d -> driver -> rollbackTransaction (); Sets the connection's database name to \a name. To have effect, the database name must be set \e{before} the connection is \l{open()} {opened}. Alternatively, you can close() the connection, set the database name, and call open() again. \note The \e{database name} is not the \e{connection name}. The connection name must be passed to addDatabase() at connection object create time. For the QSQLITE driver, if the database name specified does not exist, then it will create the file for you unless the QSQLITE_OPEN_READONLY option is set. Additionally, \a name can be set to \c ":memory:" which will create a temporary database which is only available for the lifetime of the application. For the QOCI (Oracle) driver, the database name is the TNS Service Name. For the QODBC driver, the \a name can either be a DSN, a DSN filename (in which case the file must have a \c .dsn extension), or a connection string. For example, Microsoft Access users can use the following connection string to open an \c .mdb file directly, instead of having to create a DSN entry in the ODBC manager: \snippet code/src_sql_kernel_qsqldatabase.cpp 3 There is no default value. \sa databaseName(), setUserName(), setPassword(), setHostName(), setPort(), setConnectOptions(), open() void QSqlDatabase :: setDatabaseName ( const QString & name ) if ( isValid ()) d -> dbname = name ; Sets the connection's user name to \a name. To have effect, the user name must be set \e{before} the connection is \l{open()} {opened}. Alternatively, you can close() the connection, set the user name, and call open() again. There is no default value. \sa userName(), setDatabaseName(), setPassword(), setHostName(), setPort(), setConnectOptions(), open() void QSqlDatabase :: setUserName ( const QString & name ) if ( isValid ()) d -> uname = name ; Sets the connection's password to \a password. To have effect, the password must be set \e{before} the connection is \l{open()} {opened}. Alternatively, you can close() the connection, set the password, and call open() again. There is no default value. \warning This function stores the password in plain text within Qt. Use the open() call that takes a password as parameter to avoid this behavior. \sa password(), setUserName(), setDatabaseName(), setHostName(), setPort(), setConnectOptions(), open() void QSqlDatabase :: setPassword ( const QString & password ) if ( isValid ()) d -> pword = password ; Sets the connection's host name to \a host. To have effect, the host name must be set \e{before} the connection is \l{open()} {opened}. Alternatively, you can close() the connection, set the host name, and call open() again. There is no default value. \sa hostName(), setUserName(), setPassword(), setDatabaseName(), setPort(), setConnectOptions(), open() void QSqlDatabase :: setHostName ( const QString & host ) if ( isValid ()) d -> hname = host ; Sets the connection's port number to \a port. To have effect, the port number must be set \e{before} the connection is \l{open()} {opened}. Alternatively, you can close() the connection, set the port number, and call open() again.. There is no default value. \sa port(), setUserName(), setPassword(), setHostName(), setDatabaseName(), setConnectOptions(), open() void QSqlDatabase :: setPort ( int port ) if ( isValid ()) d -> port = port ; Returns the connection's database name, which may be empty. \note The database name is not the connection name. \sa setDatabaseName() QString QSqlDatabase :: databaseName () const return d -> dbname ; Returns the connection's user name; it may be empty. \sa setUserName() QString QSqlDatabase :: userName () const return d -> uname ; Returns the connection's password. An empty string will be returned if the password was not set with setPassword(), and if the password was given in the open() call, or if no password was used. QString QSqlDatabase :: password () const return d -> pword ; Returns the connection's host name; it may be empty. \sa setHostName() QString QSqlDatabase :: hostName () const return d -> hname ; Returns the connection's driver name. \sa addDatabase(), driver() QString QSqlDatabase :: driverName () const return d -> drvName ; Returns the connection's port number. The value is undefined if the port number has not been set. \sa setPort() int QSqlDatabase :: port () const return d -> port ; Returns the database driver used to access the database connection. \sa addDatabase(), drivers() QSqlDriver * QSqlDatabase :: driver () const return d -> driver ; Returns information about the last error that occurred on the database. Failures that occur in conjunction with an individual query are reported by QSqlQuery::lastError(). \sa QSqlError, QSqlQuery::lastError() QSqlError QSqlDatabase :: lastError () const return d -> driver -> lastError (); Returns a list of the database's tables, system tables and views, as specified by the parameter \a type. \sa primaryIndex(), record() QStringList QSqlDatabase :: tables ( QSql :: TableType type ) const return d -> driver -> tables ( type ); Returns the primary index for table \a tablename. If no primary index exists, an empty QSqlIndex is returned. \note Some drivers, such as the \l {QPSQL Case Sensitivity}{QPSQL} driver, may may require you to pass \a tablename in lower case if the table was not quoted when created. See the \l{sql-driver.html}{Qt SQL driver} documentation for more information. \sa tables(), record() QSqlIndex QSqlDatabase :: primaryIndex ( const QString & tablename ) const return d -> driver -> primaryIndex ( tablename ); Returns a QSqlRecord populated with the names of all the fields in the table (or view) called \a tablename. The order in which the fields appear in the record is undefined. If no such table (or view) exists, an empty record is returned. \note Some drivers, such as the \l {QPSQL Case Sensitivity}{QPSQL} driver, may may require you to pass \a tablename in lower case if the table was not quoted when created. See the \l{sql-driver.html}{Qt SQL driver} documentation for more information. QSqlRecord QSqlDatabase :: record ( const QString & tablename ) const return d -> driver -> record ( tablename ); Sets database-specific \a options. This must be done before the connection is opened, otherwise it has no effect. Another possibility is to close the connection, call QSqlDatabase::setConnectOptions(), and open() the connection again. The format of the \a options string is a semicolon separated list of option names or option=value pairs. The options depend on the database client used and are described for each plugin in the \l{sql-driver.html}{SQL Database Drivers} page. Examples: \snippet code/src_sql_kernel_qsqldatabase.cpp 4 Refer to the client library documentation for more information about the different options. \sa connectOptions() void QSqlDatabase :: setConnectOptions ( const QString & options ) if ( isValid ()) d -> connOptions = options ; Returns the connection options string used for this connection. The string may be empty. \sa setConnectOptions() QString QSqlDatabase :: connectOptions () const return d -> connOptions ; Returns \c true if a driver called \a name is available; otherwise returns \c false. \sa drivers() bool QSqlDatabase :: isDriverAvailable ( const QString & name ) return drivers (). contains ( name ); /*! \fn QSqlDatabase QSqlDatabase::addDatabase(QSqlDriver* driver, const QString& connectionName) This overload is useful when you want to create a database connection with a \l{QSqlDriver} {driver} you instantiated yourself. It might be your own database driver, or you might just need to instantiate one of the Qt drivers yourself. If you do this, it is recommended that you include the driver code in your application. For example, you can create a PostgreSQL connection with your own QPSQL driver like this: \snippet code/src_sql_kernel_qsqldatabase_snippet.cpp 6 The above code sets up a PostgreSQL connection and instantiates a QPSQLDriver object. Next, addDatabase() is called to add the connection to the known connections so that it can be used by the Qt SQL classes. When a driver is instantiated with a connection handle (or set of handles), Qt assumes that you have already opened the database connection. \note We assume that \c qtdir is the directory where Qt is installed. This will pull in the code that is needed to use the PostgreSQL client library and to instantiate a QPSQLDriver object, assuming that you have the PostgreSQL headers somewhere in your include search path. Remember that you must link your application against the database client library. Make sure the client library is in your linker's search path, and add lines like these to your \c{.pro} file: \snippet code/src_sql_kernel_qsqldatabase_snippet.cpp 7 The method described works for all the supplied drivers. The only difference will be in the driver constructor arguments. Here is a table of the drivers included with Qt, their source code files, and their constructor arguments: \table \header \li Driver \li Class name \li Constructor arguments \li File to include \li QPSQL \li QPSQLDriver \li PGconn *connection \li \c qsql_psql.cpp \li QMYSQL \li QMYSQLDriver \li MYSQL *connection \li \c qsql_mysql.cpp \li QOCI \li QOCIDriver \li OCIEnv *environment, OCISvcCtx *serviceContext \li \c qsql_oci.cpp \li QODBC \li QODBCDriver \li SQLHANDLE environment, SQLHANDLE connection \li \c qsql_odbc.cpp \li QDB2 \li QDB2 \li SQLHANDLE environment, SQLHANDLE connection \li \c qsql_db2.cpp \li QSQLITE \li QSQLiteDriver \li sqlite *connection \li \c qsql_sqlite.cpp \li QMIMER \li QMimerSQLDriver \li MimerSession *connection \li \c qsql_mimer.cpp \li QIBASE \li QIBaseDriver \li isc_db_handle connection \li \c qsql_ibase.cpp \endtable \warning Adding a database connection with the same connection name as an existing connection, causes the existing connection to be replaced by the new one. \warning The SQL framework takes ownership of the \a driver. It must not be deleted. To remove the connection, use removeDatabase(). \sa drivers() QSqlDatabase QSqlDatabase :: addDatabase ( QSqlDriver * driver , const QString & connectionName ) QSqlDatabase db ( driver ); QSqlDatabasePrivate :: addDatabase ( db , connectionName ); return db ; Returns \c true if the QSqlDatabase has a valid driver. Example: \snippet code/src_sql_kernel_qsqldatabase.cpp 8 bool QSqlDatabase :: isValid () const return d -> driver && d -> driver != d -> shared_null ()-> driver ; Clones the database connection \a other and stores it as \a connectionName. All the settings from the original database, e.g. databaseName(), hostName(), etc., are copied across. Does nothing if \a other is an invalid database. Returns the newly created database connection. \note The new connection has not been opened. Before using the new connection, you must call open(). \reentrant QSqlDatabase QSqlDatabase :: cloneDatabase ( const QSqlDatabase & other , const QString & connectionName ) if (! other . isValid ()) return QSqlDatabase (); QSqlDatabase db ( other . driverName ()); db . d -> copy ( other . d ); QSqlDatabasePrivate :: addDatabase ( db , connectionName ); return db ; \since 5.13 \overload Clones the database connection \a other and stores it as \a connectionName. All the settings from the original database, e.g. databaseName(), hostName(), etc., are copied across. Does nothing if \a other is an invalid database. Returns the newly created database connection. \note The new connection has not been opened. Before using the new connection, you must call open(). This overload is useful when cloning the database in another thread to the one that is used by the database represented by \a other. QSqlDatabase QSqlDatabase :: cloneDatabase ( const QString & other , const QString & connectionName ) const QConnectionDict * dict = dbDict (); Q_ASSERT ( dict ); return cloneDatabase ( dict -> value_ts ( other ), connectionName ); \since 4.4 Returns the connection name, which may be empty. \note The connection name is not the \l{databaseName()} {database name}. \sa addDatabase() QString QSqlDatabase :: connectionName () const return d -> connName ; \since 4.6 Sets the default numerical precision policy used by queries created on this database connection to \a precisionPolicy. Note: Drivers that don't support fetching numerical values with low precision will ignore the precision policy. You can use QSqlDriver::hasFeature() to find out whether a driver supports this feature. Note: Setting the default precision policy to \a precisionPolicy doesn't affect any currently active queries. \sa QSql::NumericalPrecisionPolicy, numericalPrecisionPolicy(), QSqlQuery::setNumericalPrecisionPolicy(), QSqlQuery::numericalPrecisionPolicy() void QSqlDatabase :: setNumericalPrecisionPolicy ( QSql :: NumericalPrecisionPolicy precisionPolicy ) if ( driver ()) driver ()-> setNumericalPrecisionPolicy ( precisionPolicy ); d -> precisionPolicy = precisionPolicy ; \since 4.6 Returns the current default precision policy for the database connection. \sa QSql::NumericalPrecisionPolicy, setNumericalPrecisionPolicy(), QSqlQuery::numericalPrecisionPolicy(), QSqlQuery::setNumericalPrecisionPolicy() QSql :: NumericalPrecisionPolicy QSqlDatabase :: numericalPrecisionPolicy () const if ( driver ()) return driver ()-> numericalPrecisionPolicy (); return d -> precisionPolicy ; #ifndef QT_NO_DEBUG_STREAM QDebug operator <<( QDebug dbg , const QSqlDatabase & d ) QDebugStateSaver saver ( dbg ); dbg . nospace (); dbg . noquote (); if (! d . isValid ()) { dbg << "QSqlDatabase(invalid)" ; return dbg ; dbg << "QSqlDatabase(driver= \" " << d . driverName () << " \" , database= \" " << d . databaseName () << " \" , host= \" " << d . hostName () << " \" , port=" << d . port () << ", user= \" " << d . userName () << " \" , open=" << d . isOpen () << ')' ; return dbg ; #endif QT_END_NAMESPACE