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QSqlDatabase &QSqlDatabase:: operator=(const QSqlDatabase & other)Īssigns other to this object. Use addDatabase(), removeDatabase(), and database() to get valid QSqlDatabase objects. QSqlDatabase:: QSqlDatabase()Ĭreates an empty, invalid QSqlDatabase object. QSqlDatabase:: QSqlDatabase(const QSqlDatabase & other)Ĭreates a copy of other. See also SQL Database Drivers, registerSqlDriver(), and drivers().
Apex sql doc professional driver#
ODBC Driver (includes Microsoft SQL Server)Īdditional third party drivers, including your own custom drivers, can be loaded dynamically. Use contains() to see if a given connection name is in the list of connections. QSqlDatabase outputs a warning if you try to remove a connection referenced by other QSqlDatabase objects. Use removeDatabase() with a connection name to remove a connection. Use database() with a connection name to get that connection. If you create multiple database connections, specify a unique connection name for each one, when you call addDatabase(). 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 need to access an existing QSqlDatabase, it should be accessed with database(). 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. Use cloneDatabase() to create an independent database connection based on an existing one. Changes made to a database connection via one instance of QSqlDatabase will affect other instances of QSqlDatabase that represent the same connection. QSqlDatabase db = QSqlDatabase ::database()
Apex sql doc professional how to#
The following snippet shows how to create and open a default connection to a PostgreSQL database: Subsequently, the default connection will be assumed if you call any static member function without specifying the connection name. To create the default connection, don't pass the connection name argument when you call addDatabase(). QSqlDatabase also supports the concept of a default connection, which is the unnamed connection.
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You can have multiple connections to one database.
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A connection is known by its own name, not by the name of the database it connects to. See How to Write Your Own Database Driver for more information.Ĭreate a connection (i.e., an instance of QSqlDatabase) by calling one of the static addDatabase() functions, where you specify the driver or type of driver to use (depending on the type of database) and a connection name. Alternatively, you can subclass your own database driver from QSqlDriver. The connection provides access to the database via one of the supported database drivers, which are derived from QSqlDriver. An instance of QSqlDatabase represents the connection. The QSqlDatabase class provides an interface for accessing a database through a connection. Tables(QSql::TableType type = QSql::Tables) const SetNumericalPrecisionPolicy(QSql::NumericalPrecisionPolicy precisionPolicy) SetConnectOptions(const QString & options = QString()) PrimaryIndex(const QString & tablename) const Open(const QString & user, const QString & password) Exec(const QString & query = QString()) const