The QSqlDatabase class handles a connection to a database. More...

#include <qsqldatabase.h>

Collaboration diagram for QSqlDatabase:

Public Member Functions
	QSqlDatabase ()
	Creates an empty, invalid QSqlDatabase object.

	QSqlDatabase (const QSqlDatabase &other)
	Creates a copy of other.

	~QSqlDatabase ()
	Destroys the object and frees any allocated resources.

QSqlDatabase &	operator= (const QSqlDatabase &other)
	Assigns other to this object.

bool	open ()
	Executes a SQL statement on the database and returns a QSqlQuery object.

bool	open (const QString &user, const QString &password)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Opens the database connection using the given user name and password.

void	close ()
	Closes the database connection, freeing any resources acquired, and invalidating any existing QSqlQuery objects that are used with the database.

bool	isOpen () const
	Returns `true` if the database connection is currently open; otherwise returns `false`.

bool	isOpenError () const
	Returns `true` if there was an error opening the database connection; otherwise returns `false`.

QStringList	tables (QSql::TableType type=QSql::Tables) const
	Returns a list of the database's tables, system tables and views, as specified by the parameter type.

QSqlIndex	primaryIndex (const QString &tablename) const
	Returns the primary index for table tablename.

QSqlRecord	record (const QString &tablename) const
	Returns a QSqlRecord populated with the names of all the fields in the table (or view) called tablename.

QSqlError	lastError () const
	Returns information about the last error that occurred on the database.

bool	isValid () const
	Returns `true` if the QSqlDatabase has a valid driver.

bool	transaction ()
	Begins a transaction on the database if the driver supports transactions.

bool	commit ()
	Commits a transaction to the database if the driver supports transactions and a transaction() has been started.

bool	rollback ()
	Rolls back a transaction on the database, if the driver supports transactions and a transaction() has been started.

void	setDatabaseName (const QString &name)
	Sets the connection's database name to name.

void	setUserName (const QString &name)
	Sets the connection's user name to name.

void	setPassword (const QString &password)
	Sets the connection's password to password.

void	setHostName (const QString &host)
	Sets the connection's host name to host.

void	setPort (int p)
	Sets the connection's port number to port.

void	setConnectOptions (const QString &options=QString())
	Sets database-specific options.

QString	databaseName () const
	Returns the connection's database name, which may be empty.

QString	userName () const
	Returns the connection's user name; it may be empty.

QString	password () const
	Returns the connection's password.

QString	hostName () const
	Returns the connection's host name; it may be empty.

QString	driverName () const
	Returns the connection's driver name.

int	port () const
	Returns the connection's port number.

QString	connectOptions () const
	Returns the connection options string used for this connection.

QString	connectionName () const
	Returns the connection name, which may be empty.

void	setNumericalPrecisionPolicy (QSql::NumericalPrecisionPolicy precisionPolicy)
	Sets \l numericalPrecisionPolicy to precisionPolicy.

QSql::NumericalPrecisionPolicy	numericalPrecisionPolicy () const
	Returns the \l numericalPrecisionPolicy.

bool	moveToThread (QThread *targetThread)

QThread *	currentThread () const

QSqlDriver *	driver () const
	Returns the database driver used to access the database connection.

Static Public Member Functions
static QSqlDatabase	addDatabase (const QString &type, const QString &connectionName=QLatin1StringView(defaultConnection))
	\threadsafe

static QSqlDatabase	addDatabase (QSqlDriver *driver, const QString &connectionName=QLatin1StringView(defaultConnection))
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.This overload is useful when you want to create a database connection with a \l{QSqlDriver} {driver} you instantiated yourself.

static QSqlDatabase	cloneDatabase (const QSqlDatabase &other, const QString &connectionName)
	Clones the database connection other and stores it as connectionName.

static QSqlDatabase	cloneDatabase (const QString &other, const QString &connectionName)

static QSqlDatabase	database (const QString &connectionName=QLatin1StringView(defaultConnection), bool open=true)
	\threadsafe

static void	removeDatabase (const QString &connectionName)
	\threadsafe

static bool	contains (const QString &connectionName=QLatin1StringView(defaultConnection))
	\threadsafe

static QStringList	drivers ()
	Returns a list of all the available database drivers.

static QStringList	connectionNames ()
	\threadsafe

static void	registerSqlDriver (const QString &name, QSqlDriverCreatorBase *creator)
	[2]

static bool	isDriverAvailable (const QString &name)
	Returns `true` if a driver called name is available; otherwise returns `false`.

Static Public Attributes
static const char *	defaultConnection

Protected Member Functions
	QSqlDatabase (const QString &type)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Creates a QSqlDatabase connection that uses the driver referred to by type.

	QSqlDatabase (QSqlDriver *driver)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Creates a database connection using the given driver.

Properties
QSql::NumericalPrecisionPolicy	numericalPrecisionPolicy

Friends
class	QSqlDatabasePrivate

Detailed Description

The QSqlDatabase class handles a connection to a 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. A QSqlDatabase instance must only be accessed by the thread it was created in. Therefore you have to make sure to create them in the correct context. Alternatively you can change the context with QSqlDatabase::moveToThread().

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, {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, 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:

    QSqlDatabase db = QSqlDatabase::addDatabase("QPSQL");
    db.setHostName("acidalia");
    db.setDatabaseName("customdb");
    db.setUserName("mojito");
    db.setPassword("J0a1m8");
    bool 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 \l{QSqlDatabase::} {addDatabase()}. Subsequently, you can get the default connection by calling database() without the connection name argument:

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

{2,1}Some utility methods: \row
tables()
returns the list of tables \row
primaryIndex()
returns a table's primary index \row
record()
returns meta-information about a table's fields \row
transaction()
starts a transaction \row
commit()
saves and completes a transaction \row
rollback()
cancels a transaction \row
hasFeature()
checks if a driver supports transactions \row
lastError()
returns information about the last error \row
drivers()
returns the names of the available SQL drivers \row
isDriverAvailable()
checks if a particular driver is available \row
registerSqlDriver()
registers a custom-made driver \endtable

Note: When using transactions, you must start the transaction before you create your query.

See also: QSqlDriver, QSqlQuery, {Qt SQL}, {Threads and the SQL Module}

Definition at line 37 of file qsqldatabase.h.

Constructor & Destructor Documentation

◆ QSqlDatabase() [1/4]

QSqlDatabase::QSqlDatabase ( )

Creates an empty, invalid QSqlDatabase object.

Use addDatabase(), removeDatabase(), and database() to get valid QSqlDatabase objects.

Definition at line 608 of file qsqldatabase.cpp.

References QBasicAtomicInteger< T >::ref(), and QSqlDatabasePrivate::ref.

Referenced by cloneDatabase().

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◆ QSqlDatabase() [2/4]

QSqlDatabase::QSqlDatabase ( const QSqlDatabase & other )

Creates a copy of other.

Definition at line 617 of file qsqldatabase.cpp.

References other(), QBasicAtomicInteger< T >::ref(), and QSqlDatabasePrivate::ref.

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◆ ~QSqlDatabase()

QSqlDatabase::~QSqlDatabase ( )

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.

See also: close()

Definition at line 674 of file qsqldatabase.cpp.

References close(), QBasicAtomicInteger< T >::deref(), and QSqlDatabasePrivate::ref.

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◆ QSqlDatabase() [3/4]

QSqlDatabase::QSqlDatabase ( const QString & type )

explicitprotected

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.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:

\table \header

Driver Type
Description \row
QDB2
IBM DB2 \row
QIBASE
Borland InterBase Driver \row
QMYSQL
MySQL Driver \row
QOCI
Oracle Call Interface Driver \row
QODBC
ODBC Driver (includes Microsoft SQL Server) \row
QPSQL
PostgreSQL Driver \row
QSQLITE
SQLite version 3 or above \row
QMIMER
Mimer SQL 11 or above \endtable

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

See also: {SQL Database Drivers}, registerSqlDriver(), drivers()

Definition at line 586 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::init().

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◆ QSqlDatabase() [4/4]

QSqlDatabase::QSqlDatabase ( QSqlDriver * driver )

explicitprotected

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Creates a database connection using the given driver.

Definition at line 598 of file qsqldatabase.cpp.

Member Function Documentation

◆ addDatabase() [1/2]

QSqlDatabase QSqlDatabase::addDatabase	(	const QString &	type,
		const QString &	connectionName = QLatin1StringView(defaultConnection) )

static

\threadsafe

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 type is not available or could not be loaded, isValid() returns false.

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(), {Threads and the SQL Module}

Definition at line 418 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::addDatabase(), connectionName(), and db.

Referenced by QQmlLocalStorage::openDatabaseSync(), QSqlDatabase_snippets(), setmyDatabase(), and sql_intro_snippets().

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◆ addDatabase() [2/2]

QSqlDatabase QSqlDatabase::addDatabase	(	QSqlDriver *	driver,
		const QString &	connectionName = QLatin1StringView(defaultConnection) )

static

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.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:

PGconn *con = PQconnectdb("host=server user=bart password=simpson dbname=springfield");
QPSQLDriver *drv = 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:

\table \header

Driver
Class name
Constructor arguments
File to include \row
QPSQL
QPSQLDriver
PGconn *connection
qsql_psql.cpp \row
QMYSQL
QMYSQLDriver
MYSQL *connection
qsql_mysql.cpp \row
QOCI
QOCIDriver
OCIEnv *environment, OCISvcCtx *serviceContext
qsql_oci.cpp \row
QODBC
QODBCDriver
SQLHANDLE environment, SQLHANDLE connection
qsql_odbc.cpp \row
QDB2
QDB2
SQLHANDLE environment, SQLHANDLE connection
qsql_db2.cpp \row
QSQLITE
QSQLiteDriver
sqlite *connection
qsql_sqlite.cpp \row
QMIMER
QMimerSQLDriver
MimerSession *connection
qsql_mimer.cpp \row
QIBASE
QIBaseDriver
isc_db_handle connection
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.; The SQL framework takes ownership of the driver. It must not be deleted. To remove the connection, use removeDatabase().

See also: drivers()

Definition at line 1227 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::addDatabase(), connectionName(), db, and driver().

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◆ cloneDatabase() [1/2]

QSqlDatabase QSqlDatabase::cloneDatabase	(	const QSqlDatabase &	other,
		const QString &	connectionName )

static

Clones the database connection other 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().

\reentrant

Definition at line 1257 of file qsqldatabase.cpp.

References QSqlDatabase(), QSqlDatabasePrivate::addDatabase(), connectionName(), db, and other().

Referenced by cloneDatabase().

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◆ cloneDatabase() [2/2]

QSqlDatabase QSqlDatabase::cloneDatabase	(	const QString &	other,
		const QString &	connectionName )

static

Since: 5.13 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Clones the database connection other 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().

This overload is useful when cloning the database in another thread to the one that is used by the database represented by other.

Definition at line 1285 of file qsqldatabase.cpp.

References CHECK_QCOREAPPLICATION_RETVAL, cloneDatabase(), connection, connectionName(), and other().

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◆ close()

void QSqlDatabase::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()

Definition at line 749 of file qsqldatabase.cpp.

References QSqlDriver::close(), and QSqlDatabasePrivate::driver.

Referenced by ~QSqlDatabase().

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◆ commit()

bool QSqlDatabase::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 it returns {false}.

Note: For some databases, the commit will fail and return {false} if there is an \l{QSqlQuery::isActive()} {active query} using the database for a {SELECT}. Make the query \l{QSqlQuery::isActive()} {inactive} before doing the commit.

Call lastError() to get information about errors.

See also: QSqlQuery::isActive(), QSqlDriver::hasFeature(), rollback()

Definition at line 803 of file qsqldatabase.cpp.

References QSqlDriver::commitTransaction(), QSqlDatabasePrivate::driver, QSqlDriver::hasFeature(), and QSqlDriver::Transactions.

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◆ connectionName()

QString QSqlDatabase::connectionName ( ) const

Returns the connection name, which may be empty.

Note: The connection name is not the \l{databaseName()} {database name}.

See also: addDatabase()

Definition at line 1297 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::connName.

Referenced by addDatabase(), addDatabase(), cloneDatabase(), cloneDatabase(), contains(), database(), and removeDatabase().

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◆ connectionNames()

QStringList QSqlDatabase::connectionNames ( )

static

\threadsafe

Returns a list containing the names of all connections.

See also: contains(), database(), {Threads and the SQL Module}

Definition at line 553 of file qsqldatabase.cpp.

References CHECK_QCOREAPPLICATION_RETVAL.

Referenced by QQmlLocalStorage::openDatabaseSync().

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◆ connectOptions()

QString QSqlDatabase::connectOptions ( ) const

Returns the connection options string used for this connection.

The string may be empty.

See also: setConnectOptions()

Definition at line 1119 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::connOptions.

◆ contains()

bool QSqlDatabase::contains ( const QString & connectionName = QLatin1StringView(defaultConnection) )

static

\threadsafe

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

See also: connectionNames(), database(), {Threads and the SQL Module}

Definition at line 540 of file qsqldatabase.cpp.

References CHECK_QCOREAPPLICATION_RETVAL, and connectionName().

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◆ currentThread()

QThread * QSqlDatabase::currentThread ( ) const

Since: 6.8

Returns a pointer to the associated QThread instance.

Definition at line 1378 of file qsqldatabase.cpp.

References driver(), drv, and QObject::thread().

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◆ database()

QSqlDatabase QSqlDatabase::database	(	const QString &	connectionName = QLatin1StringView(defaultConnection),
		bool	open = true )

static

\threadsafe

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(), {Threads and the SQL Module}

Definition at line 439 of file qsqldatabase.cpp.

References connectionName(), QSqlDatabasePrivate::database(), and open().

Referenced by QSqlTableModel::QSqlTableModel(), QSqlTableModel::QSqlTableModel(), checkHandle(), dbQdebug(), openDatabase(), QQmlLocalStorage::openDatabaseSync(), qInit(), QSqlDatabase_snippets(), querySqlite(), removeDatabase(), and sql_intro_snippets().

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◆ databaseName()

QString QSqlDatabase::databaseName ( ) const

Returns the connection's database name, which may be empty.

Note: The database name is not the connection name.

See also: setDatabaseName()

Definition at line 955 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::dbname.

◆ driver()

QSqlDriver * QSqlDatabase::driver ( ) const

Returns the database driver used to access the database connection.

See also: addDatabase(), drivers()

Definition at line 1018 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::driver.

Referenced by addDatabase(), currentThread(), QSqlTableModelPrivate::exec(), moveToThread(), numericalPrecisionPolicy(), QRelation::populateDictionary(), qInit(), setNumericalPrecisionPolicy(), and QSqlTableModelPrivate::strippedFieldName().

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◆ driverName()

QString QSqlDatabase::driverName ( ) const

Returns the connection's driver name.

See also: addDatabase(), driver()

Definition at line 995 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::drvName.

◆ drivers()

QStringList QSqlDatabase::drivers ( )

static

Returns a list of all the available database drivers.

See also: registerSqlDriver()

Definition at line 482 of file qsqldatabase.cpp.

References CHECK_QCOREAPPLICATION_RETVAL, QListSpecialMethodsBase< T >::contains(), keyMap, and list.

Referenced by QSqlDatabasePrivate::init(), isDriverAvailable(), and testInt().

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◆ hostName()

QString QSqlDatabase::hostName ( ) const

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

See also: setHostName()

Definition at line 985 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::hname.

◆ isDriverAvailable()

bool QSqlDatabase::isDriverAvailable ( const QString & name )

static

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

See also: drivers()

Definition at line 1131 of file qsqldatabase.cpp.

References drivers().

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◆ isOpen()

bool QSqlDatabase::isOpen ( ) const

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

Definition at line 759 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::driver, and QSqlDriver::isOpen().

Referenced by QQmlLocalStorage::openDatabaseSync().

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◆ isOpenError()

bool QSqlDatabase::isOpenError ( ) const

Returns true if there was an error opening the database connection; otherwise returns false.

Error information can be retrieved using the lastError() function.

Definition at line 770 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::driver, and QSqlDriver::isOpenError().

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◆ isValid()

bool QSqlDatabase::isValid ( ) const

Returns true if the QSqlDatabase has a valid driver.

Example:

QSqlDatabase db;
qDebug() << db.isValid();    // Returns false
 
db = QSqlDatabase::database("sales");
qDebug() << db.isValid();    // Returns \c true if "sales" connection exists
 
QSqlDatabase::removeDatabase("sales");
qDebug() << db.isValid();    // Returns false

Definition at line 1240 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::driver, and QSqlDatabasePrivate::shared_null().

Referenced by qInit(), setConnectOptions(), setDatabaseName(), setHostName(), setPassword(), setPort(), and setUserName().

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◆ lastError()

QSqlError QSqlDatabase::lastError ( ) const

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, QSqlQuery::lastError()

Definition at line 1033 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::driver, and QSqlDriver::lastError().

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◆ moveToThread()

bool QSqlDatabase::moveToThread ( QThread * targetThread )

Since: 6.8

Changes the thread affinity for QSqlDatabase and its associated driver. This function returns true when the function succeeds. Event processing will continue in the targetThread.

During this operation you have to make sure that there is no QSqlQuery bound to this instance otherwise the QSqlDatabase will not be moved to the given thread and the function returns false.

Since the associated driver is derived from QObject, all constraints for moving a QObject to another thread also apply to this function.

See also: QObject::moveToThread(), {Threads and the SQL Module}

Definition at line 1357 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::connName, driver(), drv, QBasicAtomicInteger< T >::loadRelaxed(), QObject::moveToThread(), qUtf16Printable, qWarning, QSqlDatabasePrivate::ref, and QSqlDatabasePrivate::shared_null().

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◆ numericalPrecisionPolicy()

QSql::NumericalPrecisionPolicy QSqlDatabase::numericalPrecisionPolicy ( ) const

Returns the \l numericalPrecisionPolicy.

Definition at line 1333 of file qsqldatabase.cpp.

References driver(), QSqlDriver::numericalPrecisionPolicy, and QSqlDatabasePrivate::precisionPolicy.

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◆ open() [1/2]

bool QSqlDatabase::open ( )

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, lastError()

Deprecated: [6.6] Use QSqlQuery::exec() instead.

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(), setConnectOptions()

Definition at line 712 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::connOptions, QSqlDatabasePrivate::dbname, QSqlDatabasePrivate::driver, QSqlDatabasePrivate::hname, QSqlDriver::open(), QSqlDatabasePrivate::port, QSqlDatabasePrivate::pword, and QSqlDatabasePrivate::uname.

Referenced by database(), and QQmlLocalStorage::openDatabaseSync().

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◆ open() [2/2]

bool QSqlDatabase::open	(	const QString &	user,
		const QString &	password )

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.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()

Definition at line 732 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::connOptions, QSqlDatabasePrivate::dbname, QSqlDatabasePrivate::driver, QSqlDatabasePrivate::hname, QSqlDriver::open(), password(), QSqlDatabasePrivate::port, and setUserName().

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◆ operator=()

QSqlDatabase & QSqlDatabase::operator= ( const QSqlDatabase & other )

Assigns other to this object.

Definition at line 626 of file qsqldatabase.cpp.

References other(), and qAtomicAssign().

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◆ password()

QString QSqlDatabase::password ( ) const

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.

Definition at line 975 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::pword.

Referenced by open(), and setPassword().

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◆ port()

int QSqlDatabase::port ( ) const

Returns the connection's port number.

The value is undefined if the port number has not been set.

See also: setPort()

Definition at line 1006 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::port.

Referenced by setPort().

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◆ primaryIndex()

QSqlIndex QSqlDatabase::primaryIndex ( const QString & tablename ) const

Returns the primary index for table 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 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.

See also: tables(), record()

Definition at line 1063 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::driver, and QSqlDriver::primaryIndex().

Referenced by QSqlTableModelPrivate::initRecordAndPrimaryIndex().

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◆ record()

QSqlRecord QSqlDatabase::record ( const QString & tablename ) const

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.

Note: Some drivers, such as the \l {QPSQL Case Sensitivity}{QPSQL} driver, may may require you to pass 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.

Definition at line 1081 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::driver, and QSqlDriver::record().

Referenced by QSqlTableModelPrivate::initRecordAndPrimaryIndex(), and QSqlRelationalTableModel::selectStatement().

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◆ registerSqlDriver()

void QSqlDatabase::registerSqlDriver	(	const QString &	name,
		QSqlDriverCreatorBase *	creator )

static

[2]

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<QSqlDriver>);
QVERIFY(QSqlDatabase::drivers().contains("MYDRIVER"));
QSqlDatabase db = QSqlDatabase::addDatabase("MYDRIVER");
QVERIFY(db.isValid());

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

See also: drivers()

Definition at line 521 of file qsqldatabase.cpp.

References CHECK_QCOREAPPLICATION, and creator.

◆ removeDatabase()

void QSqlDatabase::removeDatabase ( const QString & connectionName )

static

\threadsafe

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("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("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(), {Threads and the SQL Module}

Definition at line 471 of file qsqldatabase.cpp.

References connectionName(), and QSqlDatabasePrivate::removeDatabase().

Referenced by dbQdebug(), openDatabase(), and removeDatabase().

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◆ rollback()

bool QSqlDatabase::rollback ( )

Rolls back a transaction on the database, if the driver supports transactions and a transaction() has been started.

Returns {true} if the operation succeeded. Otherwise it returns {false}.

Note: For some databases, the rollback will fail and return {false} if there is an \l{QSqlQuery::isActive()} {active query} using the database for a {SELECT}. Make the query \l{QSqlQuery::isActive()} {inactive} before doing the rollback.

Call lastError() to get information about errors.

See also: QSqlQuery::isActive(), QSqlDriver::hasFeature(), commit()

Definition at line 824 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::driver, QSqlDriver::hasFeature(), QSqlDriver::rollbackTransaction(), and QSqlDriver::Transactions.

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◆ setConnectOptions()

void QSqlDatabase::setConnectOptions ( const QString & options = QString() )

Sets database-specific 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 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:

db.setConnectOptions("SSL_KEY=client-key.pem;SSL_CERT=client-cert.pem;SSL_CA=ca-cert.pem;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()

Definition at line 1107 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::connOptions, and isValid().

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◆ setDatabaseName()

void QSqlDatabase::setDatabaseName ( const QString & name )

Sets the connection's database name to name.

To have effect, the database name must be set {before} the connection is \l{open()} {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 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, name can be set to ":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 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:

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

There is no default value.

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

Definition at line 867 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::dbname, and isValid().

Referenced by QQmlLocalStorage::openDatabaseSync().

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◆ setHostName()

void QSqlDatabase::setHostName ( const QString & host )

Sets the connection's host name to host.

To have effect, the host name must be set {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.

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

Definition at line 925 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::hname, and isValid().

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◆ setNumericalPrecisionPolicy()

void QSqlDatabase::setNumericalPrecisionPolicy ( QSql::NumericalPrecisionPolicy precisionPolicy )

Sets \l numericalPrecisionPolicy to precisionPolicy.

Definition at line 1323 of file qsqldatabase.cpp.

References driver(), QSqlDatabasePrivate::precisionPolicy, and QSqlDriver::setNumericalPrecisionPolicy().

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◆ setPassword()

void QSqlDatabase::setPassword ( const QString & password )

Sets the connection's password to password.

To have effect, the password must be set {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.

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

Definition at line 907 of file qsqldatabase.cpp.

References isValid(), password(), and QSqlDatabasePrivate::pword.

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◆ setPort()

void QSqlDatabase::setPort ( int port )

Sets the connection's port number to port.

To have effect, the port number must be set {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.

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

Definition at line 943 of file qsqldatabase.cpp.

References isValid(), QSqlDatabasePrivate::port, and port().

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◆ setUserName()

void QSqlDatabase::setUserName ( const QString & name )

Sets the connection's user name to name.

To have effect, the user name must be set {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.

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

Definition at line 885 of file qsqldatabase.cpp.

References isValid(), and QSqlDatabasePrivate::uname.

Referenced by open().

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◆ tables()

QStringList QSqlDatabase::tables ( QSql::TableType type = QSql::Tables ) const

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

See also: primaryIndex(), record()

Definition at line 1046 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::driver, and QSqlDriver::tables().

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◆ transaction()

bool QSqlDatabase::transaction ( )

Begins a transaction on the database if the driver supports transactions.

Returns {true} if the operation succeeded. Otherwise it returns {false}.

See also: QSqlDriver::hasFeature(), commit(), rollback()

Definition at line 782 of file qsqldatabase.cpp.

References QSqlDriver::beginTransaction(), QSqlDatabasePrivate::driver, QSqlDriver::hasFeature(), and QSqlDriver::Transactions.

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◆ userName()

QString QSqlDatabase::userName ( ) const

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

See also: setUserName()

Definition at line 965 of file qsqldatabase.cpp.

References QSqlDatabasePrivate::uname.

Friends And Related Symbol Documentation

◆ QSqlDatabasePrivate

friend class QSqlDatabasePrivate

friend

Definition at line 111 of file qsqldatabase.h.

Member Data Documentation

◆ defaultConnection

const char* QSqlDatabase::defaultConnection

static

Definition at line 89 of file qsqldatabase.h.

Referenced by qInit().

Property Documentation

◆ numericalPrecisionPolicy

QSqlDatabase::numericalPrecisionPolicy

readwrite

Since: 6.8

This property holds the default numerical precision policy used by queries created on this database connection.

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 precisionPolicy doesn't affect any currently active queries.

See also: QSql::NumericalPrecisionPolicy, QSqlQuery::numericalPrecisionPolicy, QSqlDriver::numericalPrecisionPolicy

Definition at line 41 of file qsqldatabase.h.

The documentation for this class was generated from the following files:

qtbase/src/sql/kernel/qsqldatabase.h (b4c63b89dfe136d0579bf1b6422c4d878cdd74ab)
qtbase/src/sql/doc/snippets/code/src_sql_kernel_qsqldatabase_snippet.cpp (05fc3aef53348fb58be6308076e000825b704e58)
qtbase/src/sql/kernel/qsqldatabase.cpp (b4c63b89dfe136d0579bf1b6422c4d878cdd74ab)

Public Member Functions

Static Public Member Functions

Static Public Attributes

Protected Member Functions

Properties

Friends

Detailed Description

Constructor & Destructor Documentation

◆ QSqlDatabase() [1/4]

◆ QSqlDatabase() [2/4]

◆ ~QSqlDatabase()

◆ QSqlDatabase() [3/4]

◆ QSqlDatabase() [4/4]

Member Function Documentation

◆ addDatabase() [1/2]

◆ addDatabase() [2/2]

◆ cloneDatabase() [1/2]

◆ cloneDatabase() [2/2]

◆ close()

◆ commit()

◆ connectionName()

◆ connectionNames()

◆ connectOptions()

◆ contains()

◆ currentThread()

◆ database()

◆ databaseName()

◆ driver()

◆ driverName()

◆ drivers()

◆ hostName()

◆ isDriverAvailable()

◆ isOpen()

◆ isOpenError()

◆ isValid()

◆ lastError()

◆ moveToThread()

◆ numericalPrecisionPolicy()

◆ open() [1/2]

◆ open() [2/2]

◆ operator=()

◆ password()

◆ port()

◆ primaryIndex()

◆ record()

◆ registerSqlDriver()

◆ removeDatabase()

◆ rollback()

◆ setConnectOptions()

◆ setDatabaseName()

◆ setHostName()

◆ setNumericalPrecisionPolicy()

◆ setPassword()

◆ setPort()

◆ setUserName()

◆ tables()

◆ transaction()

◆ userName()

Friends And Related Symbol Documentation

◆ QSqlDatabasePrivate

Member Data Documentation

◆ defaultConnection

Property Documentation

◆ numericalPrecisionPolicy