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## com.trolltech.qt.sql
Class QSqlDatabase

    java.lang.Object
      com.trolltech.qt.internal.QSignalEmitterInternal
          com.trolltech.qt.QSignalEmitter
              com.trolltech.qt.QtJambiObject
                  com.trolltech.qt.sql.QSqlDatabase

All Implemented Interfaces:
  QtJambiInterface, java.lang.Cloneable

    public class QSqlDatabase

extends QtJambiObject
implements java.lang.Cloneable

The `QSqlDatabase` class represents a connection to a database. 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 supported database drivers, which are derived from `QSqlDriver`. Alternatively, you can subclass your own database driver from `QSqlDriver`. See 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 the driver or type of driver to use (i.e., what kind of database will you access?) and a connection name. A connection is known by its own name, 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 default connection, which is the unnamed connection. To create the default connection, don't pass the connection name argument when you call `addDatabase()`. Subsequently, when you call any static member function that takes the connection name argument, if you don't pass the connection name argument, the default connection is assumed. The following snippet shows how to create and open a default connection to a MySQL database:

            QSqlDatabase db = QSqlDatabase.addDatabase("QPSQL");
            db.setHostName("apollo");
            db.setDatabaseName("customdb");
            db.setUserName("mojito");
            db.setPassword("J0a1m8");
            boolean ok = db.open();

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 default connection, because we didn't give a connection name to `addDatabase()`. Subsequently, you can get the default connection by calling `database()` without the connection name argument:

            QSqlDatabase db = QSqlDatabase.database();

`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.

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.

Once a connection is established, you can call `tables()` to get the list of tables in the database, call `primaryIndex()` to get a table's primary index, and call `record()` to get meta-information about a table's fields (e.g., field names).

Note:`QSqlDatabase::exec()` is deprecated. Use `QSqlQuery::exec()` instead.

If the driver supports transactions, use `transaction()` to start a transaction, and `commit()` or `rollback()` to complete it. Use `hasFeature()` to ask if the driver supports transactions. Note: When using transactions, you must start the transaction before you create your query.

If an error occurrs, `lastError()` will return information about it.

Get the names of the available SQL drivers with `drivers()`. Check for the presence of a particular driver with `isDriverAvailable()`. If you have created your own custom driver, you must register it with `registerSqlDriver()`.

See also:
  `QSqlDriver`, `QSqlQuery`, QtSql Module, and Threads and the SQL Module.

Nested Class Summary

Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
`QSignalEmitter.AbstractSignal, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9`

Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
`com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal`

Field Summary

Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
`currentSender`

Constructor Summary
`` | `QSqlDatabase()` Creates an empty, invalid `QSqlDatabase` object.
`` | `QSqlDatabase(QSqlDatabase other)` Creates a copy of `other`.
`protected` | `QSqlDatabase(QSqlDriver driver)` Creates a database connection using the given `driver`.
`protected` | `QSqlDatabase(java.lang.String type)` Creates a `QSqlDatabase` connection that uses the driver referred to by `type`.

Method Summary
`static QSqlDatabase` | `addDatabase(QSqlDriver driver)` This overload is useful when you want to create a database connection with a `driver` you instantiated yourself.
`static QSqlDatabase` | `addDatabase(QSqlDriver driver, java.lang.String connectionName)` This overload is useful when you want to create a database connection with a `driver` you instantiated yourself.
`static QSqlDatabase` | `addDatabase(java.lang.String type)` Adds a database to the list of database connections using the driver `type` and the connection name `connectionName`.
`static QSqlDatabase` | `addDatabase(java.lang.String type, java.lang.String connectionName)` Adds a database to the list of database connections using the driver `type` and the connection name `connectionName`.
`QSqlDatabase` | `clone()` This method is reimplemented for internal reasons
`static QSqlDatabase` | `cloneDatabase(QSqlDatabase other, java.lang.String connectionName)` Clones the database connection `other` and and stores it as `connectionName`.
`void` | `close()` Closes the database connection, freeing any resources acquired, and invalidating any existing `QSqlQuery` objects that are used with the database.
`boolean` | `commit()` Commits a transaction to the database if the driver supports transactions and a `transaction()` has been started.
`java.lang.String` | `connectionName()` Returns the connection name, which may be empty.
`static java.util.List` | `connectionNames()` Returns a list containing the names of all connections.
`java.lang.String` | `connectOptions()` Returns the connection options string used for this connection.
`static boolean` | `contains()` Returns true if the list of database connections contains `connectionName`; otherwise returns false.
`static boolean` | `contains(java.lang.String connectionName)` Returns true if the list of database connections contains `connectionName`; otherwise returns false.
`static QSqlDatabase` | `database()` Returns the database connection called `connectionName`.
`static QSqlDatabase` | `database(java.lang.String connectionName)` Returns the database connection called `connectionName`.
`static QSqlDatabase` | `database(java.lang.String connectionName, boolean open)` Returns the database connection called `connectionName`.
`java.lang.String` | `databaseName()` Returns the connection's database name, which may be empty.
`static java.lang.String` | `defaultConnection()` Returns this QSqlDatabase's default connection.
`QSqlDriver` | `driver()` Returns the database driver used to access the database connection.
`java.lang.String` | `driverName()` Returns the connection's driver name.
`static java.util.List` | `drivers()` Returns a list of all the available database drivers.
`QSqlQuery` | `exec()` Executes a SQL statement on the database and returns a `QSqlQuery` object.
`QSqlQuery` | `exec(java.lang.String query)` Executes a SQL statement on the database and returns a `QSqlQuery` object.
`java.lang.String` | `hostName()` Returns the connection's host name; it may be empty.
`static boolean` | `isDriverAvailable(java.lang.String name)` Returns true if a driver called `name` is available; otherwise returns false.
`boolean` | `isOpen()` Returns true if the database connection is currently open; otherwise returns false.
`boolean` | `isOpenError()` Returns true if there was an error opening the database connection; otherwise returns false.
`boolean` | `isValid()` Returns true if the `QSqlDatabase` has a valid driver.
`QSqlError` | `lastError()` Returns information about the last error that occurred on the database.
`boolean` | `open()` Opens the database connection using the current connection values.
`boolean` | `open(java.lang.String user, java.lang.String password)` Opens the database connection using the given `user` name and `password`.
`java.lang.String` | `password()` Returns the connection's password.
`int` | `port()` Returns the connection's port number.
`QSqlIndex` | `primaryIndex(java.lang.String tablename)` Returns the primary index for table `tablename`.
`QSqlRecord` | `record(java.lang.String tablename)` Returns a `QSqlRecord` populated with the names of all the fields in the table (or view) called `tablename`.
`static void` | `registerSqlDriver(java.lang.String name, QSqlDriverCreatorBase creator)` This function registers a new SQL driver called `name`, within the SQL framework.
`static void` | `removeDatabase(java.lang.String connectionName)` Removes the database connection `connectionName` from the list of database connections.
`boolean` | `rollback()` Rolls a transaction back on the database if the driver supports transactions and a `transaction()` has been started.
`void` | `setConnectOptions()` Sets database-specific `options`.
`void` | `setConnectOptions(java.lang.String options)` Sets database-specific `options`.
`void` | `setDatabaseName(java.lang.String name)` Sets the connection's database name to `name`.
`void` | `setHostName(java.lang.String host)` Sets the connection's host name to `host`.
`void` | `setPassword(java.lang.String password)` Sets the connection's password to `password`.
`void` | `setPort(int p)` Sets the connection's port number to `port`.
`void` | `setUserName(java.lang.String name)` Sets the connection's user name to `name`.
`java.util.List` | `tables()` This is an overloaded method provided for convenience.
`java.util.List` | `tables(QSql.TableType type)` Returns a list of the database's tables, system tables and views, as specified by the parameter `type`.
`java.lang.String` | `toString()` Returns a string representation of the `this QSqlDatabase`.
`boolean` | `transaction()` Begins a transaction on the database if the driver supports transactions.
`java.lang.String` | `userName()` Returns the connection's user name; it may be empty.

Methods inherited from class com.trolltech.qt.QtJambiObject
`dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr`

Methods inherited from class com.trolltech.qt.QSignalEmitter
`blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread`

Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
`__qt_signalInitialization`

Methods inherited from class java.lang.Object
`getClass, hashCode, notify, notifyAll, wait, wait, wait`

Methods inherited from interface com.trolltech.qt.QtJambiInterface
`disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership`

Constructor Detail

### QSqlDatabase

    public QSqlDatabase()

  Creates an empty, invalid `QSqlDatabase` object. Use `addDatabase()`, `removeDatabase()`, and `database()` to get valid `QSqlDatabase` objects.

### QSqlDatabase

    protected QSqlDatabase(QSqlDriver driver)

  Creates a database connection using the given `driver`.

### QSqlDatabase

    public QSqlDatabase(QSqlDatabase other)

  Creates a copy of `other`.

### QSqlDatabase

    protected QSqlDatabase(java.lang.String type)

  Creates a `QSqlDatabase` connection that uses the driver referred to by `type`. If the `type` is not recognized, the database connection will have no functionality.

  The currently available driver types are:

  Driver Type | Description
  --- | ---
  QDB2 | IBM DB2
  QIBASE | Borland InterBase Driver
  QMYSQL | MySQL Driver
  QOCI | Oracle Call Interface Driver
  QODBC | ODBC Driver (includes Microsoft SQL Server)
  QPSQL | PostgreSQL Driver
  QSQLITE | SQLite version 3 or above
  QSQLITE2 | SQLite version 2
  QTDS | Sybase Adaptive Server

  Additional third party drivers, including your own custom drivers, can be loaded dynamically.

See also:
  SQL Database Drivers, `registerSqlDriver()`, and `drivers()`.

Method Detail

### close

    public final void close()

  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.

See also:
  `removeDatabase()`.

### commit

    public final boolean commit()

  Commits a transaction to the database if the driver supports transactions and a `transaction()` has been started. Returns true if the operation succeeded; otherwise returns false.

  Note that on some databases, this function will not work if there is an active `QSqlQuery` on the database. Use the `lastError()` function to retrieve database-specific error data about the error that occurred.

See also:
  `QSqlDriver::hasFeature()`, and `rollback()`.

### connectOptions

    public final java.lang.String connectOptions()

  Returns the connection options string used for this connection. The string may be empty.

See also:
  `setConnectOptions()`.

### connectionName

    public final java.lang.String connectionName()

  Returns the connection name, which may be empty. Note: The connection name is not the `database name`.

See also:
  `addDatabase()`.

### databaseName

    public final java.lang.String databaseName()

  Returns the connection's database name, which may be empty. Note: The database name is not the connection name.

See also:
  `setDatabaseName()`.

### driver

    public final QSqlDriver driver()

  Returns the database driver used to access the database connection.

See also:
  `addDatabase()`, and `drivers()`.

### driverName

    public final java.lang.String driverName()

  Returns the connection's driver name.

See also:
  `addDatabase()`, and `driver()`.

### exec

    public final QSqlQuery exec()

  Executes a SQL statement on the database and returns a `QSqlQuery` object. Use `lastError()` to retrieve error information. If `query` is empty, an empty, invalid query is returned and `lastError()` is not affected.

See also:
  `QSqlQuery`, and `lastError()`.

### exec

    public final QSqlQuery exec(java.lang.String query)

  Executes a SQL statement on the database and returns a `QSqlQuery` object. Use `lastError()` to retrieve error information. If `query` is empty, an empty, invalid query is returned and `lastError()` is not affected.

See also:
  `QSqlQuery`, and `lastError()`.

### hostName

    public final java.lang.String hostName()

  Returns the connection's host name; it may be empty.

See also:
  `setHostName()`.

### isOpen

    public final boolean isOpen()

  Returns true if the database connection is currently open; otherwise returns false.

### isOpenError

    public final boolean isOpenError()

  Returns true if there was an error opening the database connection; otherwise returns false. Error information can be retrieved using the `lastError()` function.

### isValid

    public final boolean isValid()

  Returns true if the `QSqlDatabase` has a valid driver.

  Example:

              QSqlDatabase db = new QSqlDatabase();
              System.out.println(db.isValid());    // Returns false

              db = QSqlDatabase.database("sales");
              System.out.println(db.isValid());    // Returns true if "sales" connection exists

              QSqlDatabase.removeDatabase("sales");
              System.out.println(db.isValid());    // Returns false

### lastError

    public final QSqlError lastError()

  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()`.

See also:
  `QSqlError`, and `QSqlQuery::lastError()`.

### open

    public final boolean open()

  Opens the database connection using the current connection values. Returns true on success; otherwise returns false. Error information can be retrieved using `lastError()`.

See also:
  `lastError()`, `setDatabaseName()`, `setUserName()`, `setPassword()`, `setHostName()`, `setPort()`, and `setConnectOptions()`.

### open

    public final boolean open(java.lang.String user,
                              java.lang.String password)

  Opens the database connection using the given `user` name and `password`. Returns true on success; otherwise returns 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.

See also:
  `lastError()`.

### password

    public final java.lang.String password()

  Returns the connection's password. If the password was not set with `setPassword()`, and if the password was given in the `open()` call, or if no password was used, an empty string is returned.

See also:
  `setPassword()`.

### port

    public final int port()

  Returns the connection's port number. The value is undefined if the port number has not been set.

See also:
  `setPort()`.

### primaryIndex

    public final QSqlIndex primaryIndex(java.lang.String tablename)

  Returns the primary index for table `tablename`. If no primary index exists an empty `QSqlIndex` is returned.

See also:
  `tables()`, and `record()`.

### record

    public final QSqlRecord record(java.lang.String tablename)

  Returns a `QSqlRecord` populated with the names of all the fields in the table (or view) called `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.

### rollback

    public final boolean rollback()

  Rolls a transaction back on the database if the driver supports transactions and a `transaction()` has been started. Returns true if the operation succeeded; otherwise returns false.

See also:
  `QSqlDriver::hasFeature()`, and `commit()`.

### setConnectOptions

    public final void setConnectOptions()

  Sets database-specific `options`. This must be done before the connection is opened or it has no effect (or you can `close()` the connection, call this function and `open()` the connection again).

  The format of the `options` string is a semicolon separated list of option names or option=value pairs. The options depend on the database client used:

  ODBC | MySQL | PostgreSQL
  --- | --- | ---
  SQL_ATTR_ACCESS_MODE SQL_ATTR_LOGIN_TIMEOUT SQL_ATTR_CONNECTION_TIMEOUT SQL_ATTR_CURRENT_CATALOG SQL_ATTR_METADATA_ID SQL_ATTR_PACKET_SIZE SQL_ATTR_TRACEFILE SQL_ATTR_TRACE SQL_ATTR_CONNECTION_POOLING SQL_ATTR_ODBC_VERSION | CLIENT_COMPRESS CLIENT_FOUND_ROWS CLIENT_IGNORE_SPACE CLIENT_SSL CLIENT_ODBC CLIENT_NO_SCHEMA CLIENT_INTERACTIVE UNIX_SOCKET | connect_timeout options tty requiressl service
  DB2 | OCI | TDS
  SQL_ATTR_ACCESS_MODE SQL_ATTR_LOGIN_TIMEOUT | OCI_ATTR_PREFETCH_ROWS OCI_ATTR_PREFETCH_MEMORY | none
  SQLite | Interbase
  QSQLITE_BUSY_TIMEOUT | ISC_DPB_LC_CTYPE ISC_DPB_SQL_ROLE_NAME

  Examples:

          // ...
          // MySQL connection
          db.setConnectOptions("CLIENT_SSL=1;CLIENT_IGNORE_SPACE=1"); // use an SSL connection to the server
          if (!db.open()) {
              db.setConnectOptions(); // clears the connect option string
          // ...
          }
          // ...
          // PostgreSQL connection
          db.setConnectOptions("requiressl=1"); // enable PostgreSQL SSL connections
          if (!db.open()) {
              db.setConnectOptions(); // clear options
              // ...
          }
          // ...
          // ODBC connection
          db.setConnectOptions("SQL_ATTR_ACCESS_MODE=SQL_MODE_READ_ONLY;SQL_ATTR_TRACE=SQL_OPT_TRACE_ON"); // set ODBC options
          if (!db.open()) {
              db.setConnectOptions(); // don't try to set this option
              // ...
          }

  Refer to the client library documentation for more information about the different options.

See also:
  `connectOptions()`.

### setConnectOptions

    public final void setConnectOptions(java.lang.String options)

  Sets database-specific `options`. This must be done before the connection is opened or it has no effect (or you can `close()` the connection, call this function and `open()` the connection again).

  The format of the `options` string is a semicolon separated list of option names or option=value pairs. The options depend on the database client used:

  ODBC | MySQL | PostgreSQL
  --- | --- | ---
  SQL_ATTR_ACCESS_MODE SQL_ATTR_LOGIN_TIMEOUT SQL_ATTR_CONNECTION_TIMEOUT SQL_ATTR_CURRENT_CATALOG SQL_ATTR_METADATA_ID SQL_ATTR_PACKET_SIZE SQL_ATTR_TRACEFILE SQL_ATTR_TRACE SQL_ATTR_CONNECTION_POOLING SQL_ATTR_ODBC_VERSION | CLIENT_COMPRESS CLIENT_FOUND_ROWS CLIENT_IGNORE_SPACE CLIENT_SSL CLIENT_ODBC CLIENT_NO_SCHEMA CLIENT_INTERACTIVE UNIX_SOCKET | connect_timeout options tty requiressl service
  DB2 | OCI | TDS
  SQL_ATTR_ACCESS_MODE SQL_ATTR_LOGIN_TIMEOUT | OCI_ATTR_PREFETCH_ROWS OCI_ATTR_PREFETCH_MEMORY | none
  SQLite | Interbase
  QSQLITE_BUSY_TIMEOUT | ISC_DPB_LC_CTYPE ISC_DPB_SQL_ROLE_NAME

  Examples:

          // ...
          // MySQL connection
          db.setConnectOptions("CLIENT_SSL=1;CLIENT_IGNORE_SPACE=1"); // use an SSL connection to the server
          if (!db.open()) {
              db.setConnectOptions(); // clears the connect option string
          // ...
          }
          // ...
          // PostgreSQL connection
          db.setConnectOptions("requiressl=1"); // enable PostgreSQL SSL connections
          if (!db.open()) {
              db.setConnectOptions(); // clear options
              // ...
          }
          // ...
          // ODBC connection
          db.setConnectOptions("SQL_ATTR_ACCESS_MODE=SQL_MODE_READ_ONLY;SQL_ATTR_TRACE=SQL_OPT_TRACE_ON"); // set ODBC options
          if (!db.open()) {
              db.setConnectOptions(); // don't try to set this option
              // ...
          }

  Refer to the client library documentation for more information about the different options.

See also:
  `connectOptions()`.

### setDatabaseName

    public final void setDatabaseName(java.lang.String name)

  Sets the connection's database name to `name`. To have effect, the database name must be set before the connection is `opened`. Alternatively, you can `close()` the connection, set the database name, and call `open()` again. Note: The database name is not the connection name. The connection name must be passed to `addDatabase()` at connection object create time.

  For the QOCI (Oracle) driver, the database name is the TNS Service Name.

  For the QODBC driver, the `name` can either be a DSN, a DSN filename (in which case the file must have a `.dsn` extension), or a connection string.

  For example, Microsoft Access users can use the following connection string to open an `.mdb` file directly, instead of having to create a DSN entry in the ODBC manager:

          // ...
          db = QSqlDatabase.addDatabase("QODBC");
          db.setDatabaseName("DRIVER={Microsoft Access Driver (*.mdb)};FIL={MS Access};DBQ=myaccessfile.mdb");
          if (db.open()) {
              // success!
          }
          // ...

  There is no default value.

See also:
  `databaseName()`, `setUserName()`, `setPassword()`, `setHostName()`, `setPort()`, `setConnectOptions()`, and `open()`.

### setHostName

    public final void setHostName(java.lang.String host)

  Sets the connection's host name to `host`. To have effect, the host name must be set before the connection is `opened`. Alternatively, you can `close()` the connection, set the host name, and call `open()` again.

  There is no default value.

See also:
  `hostName()`, `setUserName()`, `setPassword()`, `setDatabaseName()`, `setPort()`, `setConnectOptions()`, and `open()`.

### setPassword

    public final void setPassword(java.lang.String password)

  Sets the connection's password to `password`. To have effect, the password must be set before the connection is `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.

See also:
  `password()`, `setUserName()`, `setDatabaseName()`, `setHostName()`, `setPort()`, `setConnectOptions()`, and `open()`.

### setPort

    public final void setPort(int p)

  Sets the connection's port number to `port`. To have effect, the port number must be set before the connection is `opened`. Alternatively, you can `close()` the connection, set the port number, and call `open()` again..

  There is no default value.

See also:
  `port()`, `setUserName()`, `setPassword()`, `setHostName()`, `setDatabaseName()`, `setConnectOptions()`, and `open()`.

### setUserName

    public final void setUserName(java.lang.String name)

  Sets the connection's user name to `name`. To have effect, the user name must be set before the connection is `opened`. Alternatively, you can `close()` the connection, set the user name, and call `open()` again.

  There is no default value.

See also:
  `userName()`, `setDatabaseName()`, `setPassword()`, `setHostName()`, `setPort()`, `setConnectOptions()`, and `open()`.

### tables

    public final java.util.List tables()

  This is an overloaded method provided for convenience.

### tables

    public final java.util.List tables(QSql.TableType type)

  Returns a list of the database's tables, system tables and views, as specified by the parameter `type`.

See also:
  `primaryIndex()`, and `record()`.

### transaction

    public final boolean transaction()

  Begins a transaction on the database if the driver supports transactions. Returns true if the operation succeeded; otherwise returns false.

See also:
  `QSqlDriver::hasFeature()`, `commit()`, and `rollback()`.

### userName

    public final java.lang.String userName()

  Returns the connection's user name; it may be empty.

See also:
  `setUserName()`.

### addDatabase

    public static QSqlDatabase addDatabase(QSqlDriver driver)

  This overload is useful when you want to create a database connection with a `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:

              #include "qtdir/src/sql/drivers/psql/qsql_psql.cpp"

          PGconn on = PQconnectdb("host=server user=bart password=simpson dbname=springfield");
              QPSQLDriver rv =  new QPSQLDriver(con);
              QSqlDatabase db = QSqlDatabase.addDatabase(drv); // becomes the new default connection
              QSqlQuery query;
              query.exec("SELECT NAME, ID FROM STAFF");
              // ...

  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 `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 `.pro` file:

               unix:LIBS += -lpq
           win32:LIBS += libpqdll.lib

  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:

  Driver | Class name | Constructor arguments | File to include
  --- | --- | --- | ---
  QPSQL | QPSQLDriver | PGconn *connection | `qsql_psql.cpp`
  QMYSQL | QMYSQLDriver | MYSQL *connection | `qsql_mysql.cpp`
  QOCI | QOCIDriver | OCIEnv *environment, OCISvcCtx *serviceContext | `qsql_oci.cpp`
  QODBC | QODBCDriver | SQLHANDLE environment, SQLHANDLE connection | `qsql_odbc.cpp`
  QDB2 | QDB2 | SQLHANDLE environment, SQLHANDLE connection | `qsql_db2.cpp`
  QTDS | QTDSDriver | LOGINREC *loginRecord, DBPROCESS *dbProcess, const QString &hostName | `qsql_tds.cpp`
  QSQLITE | QSQLiteDriver | sqlite *connection | `qsql_sqlite.cpp`
  QIBASE | QIBaseDriver | isc_db_handle connection | `qsql_ibase.cpp`

  The host name (or service name) is needed when constructing the QTDSDriver for creating new connections for internal queries. This is to prevent blocking when several `QSqlQuery` objects are used simultaneously.

  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 `driver`. It must not be deleted. To remove the connection, use `removeDatabase()`.

See also:
  `drivers()`.

### addDatabase

    public static QSqlDatabase addDatabase(QSqlDriver driver,
                                           java.lang.String connectionName)

  This overload is useful when you want to create a database connection with a `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:

              #include "qtdir/src/sql/drivers/psql/qsql_psql.cpp"

          PGconn on = PQconnectdb("host=server user=bart password=simpson dbname=springfield");
              QPSQLDriver rv =  new QPSQLDriver(con);
              QSqlDatabase db = QSqlDatabase.addDatabase(drv); // becomes the new default connection
              QSqlQuery query;
              query.exec("SELECT NAME, ID FROM STAFF");
              // ...

  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 `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 `.pro` file:

               unix:LIBS += -lpq
           win32:LIBS += libpqdll.lib

  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:

  Driver | Class name | Constructor arguments | File to include
  --- | --- | --- | ---
  QPSQL | QPSQLDriver | PGconn *connection | `qsql_psql.cpp`
  QMYSQL | QMYSQLDriver | MYSQL *connection | `qsql_mysql.cpp`
  QOCI | QOCIDriver | OCIEnv *environment, OCISvcCtx *serviceContext | `qsql_oci.cpp`
  QODBC | QODBCDriver | SQLHANDLE environment, SQLHANDLE connection | `qsql_odbc.cpp`
  QDB2 | QDB2 | SQLHANDLE environment, SQLHANDLE connection | `qsql_db2.cpp`
  QTDS | QTDSDriver | LOGINREC *loginRecord, DBPROCESS *dbProcess, const QString &hostName | `qsql_tds.cpp`
  QSQLITE | QSQLiteDriver | sqlite *connection | `qsql_sqlite.cpp`
  QIBASE | QIBaseDriver | isc_db_handle connection | `qsql_ibase.cpp`

  The host name (or service name) is needed when constructing the QTDSDriver for creating new connections for internal queries. This is to prevent blocking when several `QSqlQuery` objects are used simultaneously.

  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 `driver`. It must not be deleted. To remove the connection, use `removeDatabase()`.

See also:
  `drivers()`.

### addDatabase

    public static QSqlDatabase addDatabase(java.lang.String type)

  Adds a database to the list of database connections using the driver `type` and the connection name `connectionName`. If there already exists a database connection called `connectionName`, that connection is removed.

  The database connection is referred to by `connectionName`. The newly added database connection is returned.

  If `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 `connectionName` is provided here, use database(`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 `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()`.

See also:
  `database()`, `removeDatabase()`, and Threads and the SQL Module.

### addDatabase

    public static QSqlDatabase addDatabase(java.lang.String type,
                                           java.lang.String connectionName)

  Adds a database to the list of database connections using the driver `type` and the connection name `connectionName`. If there already exists a database connection called `connectionName`, that connection is removed.

  The database connection is referred to by `connectionName`. The newly added database connection is returned.

  If `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 `connectionName` is provided here, use database(`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 `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()`.

See also:
  `database()`, `removeDatabase()`, and Threads and the SQL Module.

### cloneDatabase

    public static QSqlDatabase cloneDatabase(QSqlDatabase other,
                                             java.lang.String connectionName)

  Clones the database connection `other` and and stores it as `connectionName`. All the settings from the original database, e.g. `databaseName()`, `hostName()`, etc., are copied across. Does nothing if `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()`.

### connectionNames

    public static java.util.List connectionNames()

  Returns a list containing the names of all connections.

See also:
  `contains()`, `database()`, and Threads and the SQL Module.

### contains

    public static boolean contains()

  Returns true if the list of database connections contains `connectionName`; otherwise returns false.

See also:
  `connectionNames()`, `database()`, and Threads and the SQL Module.

### contains

    public static boolean contains(java.lang.String connectionName)

  Returns true if the list of database connections contains `connectionName`; otherwise returns false.

See also:
  `connectionNames()`, `database()`, and Threads and the SQL Module.

### database

    public static QSqlDatabase database(java.lang.String connectionName)

  Returns the database connection called `connectionName`. The database connection must have been previously added with `addDatabase()`. If `open` is true (the default) and the database connection is not already open it is opened now. If no `connectionName` is specified the default connection is used. If `connectionName` does not exist in the list of databases, an invalid connection is returned.

See also:
  `isOpen()`, and Threads and the SQL Module.

### database

    public static QSqlDatabase database()

  Returns the database connection called `connectionName`. The database connection must have been previously added with `addDatabase()`. If `open` is true (the default) and the database connection is not already open it is opened now. If no `connectionName` is specified the default connection is used. If `connectionName` does not exist in the list of databases, an invalid connection is returned.

See also:
  `isOpen()`, and Threads and the SQL Module.

### database

    public static QSqlDatabase database(java.lang.String connectionName,
                                        boolean open)

  Returns the database connection called `connectionName`. The database connection must have been previously added with `addDatabase()`. If `open` is true (the default) and the database connection is not already open it is opened now. If no `connectionName` is specified the default connection is used. If `connectionName` does not exist in the list of databases, an invalid connection is returned.

See also:
  `isOpen()`, and Threads and the SQL Module.

### drivers

    public static java.util.List drivers()

  Returns a list of all the available database drivers.

See also:
  `registerSqlDriver()`.

### isDriverAvailable

    public static boolean isDriverAvailable(java.lang.String name)

  Returns true if a driver called `name` is available; otherwise returns false.

See also:
  `drivers()`.

### registerSqlDriver

    public static void registerSqlDriver(java.lang.String name,
                                         QSqlDriverCreatorBase creator)

  This function registers a new SQL driver called `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:

           QSqlDatabase.registerSqlDriver("MYDRIVER",
                                           new QSqlDriverCreator<MyDatabaseDriver>);
           QSqlDatabase db = QSqlDatabase.addDatabase("MYDRIVER");

  `QSqlDatabase` takes ownership of the `creator` pointer, so you mustn't delete it yourself.

See also:
  `drivers()`.

### removeDatabase

    public static void removeDatabase(java.lang.String connectionName)

  Removes the database connection `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:

          // WRONG
          QSqlDatabase db = QSqlDatabase.database("sales");
          QSqlQuery query = new QSqlQuery("SELECT NAME, DOB FROM EMPLOYEES", db);
          QSqlDatabase.removeDatabase("sales"); // will output a warning

          // "db" is now a dangling invalid database connection,
          // "query" contains an invalid result set

  The correct way to do it:

          {
              QSqlDatabase db = QSqlDatabase.database("sales");
              QSqlQuery query = new QSqlQuery("SELECT NAME, DOB FROM EMPLOYEES", db);
          }
          // Both "db" and "query" are destroyed because they are out of scope
          QSqlDatabase.removeDatabase("sales"); // correct

  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.

See also:
  `database()`, `connectionName()`, and Threads and the SQL Module.

### defaultConnection

    public static java.lang.String defaultConnection()

  Returns this QSqlDatabase's default connection.

### toString

    public java.lang.String toString()

  Returns a string representation of the `this QSqlDatabase`.

  Overrides:
    `toString` in class `java.lang.Object`

### clone

    public QSqlDatabase clone()

  This method is reimplemented for internal reasons

  Overrides:
    `clone` in class `java.lang.Object`

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