qsqldatabase.3qt

linux下GUI编程工具qt的在线连接帮助手册

'\" t
.TH QSqlDatabase 3qt "11 October 2001" "Trolltech AS" \" -*- nroff -*-
.\" Copyright 1992-2001 Trolltech AS.  All rights reserved.  See the
.\" license file included in the distribution for a complete license
.\" statement.
.\"
.ad l
.nh
.SH NAME
QSqlDatabase \- Used to create SQL database connections and provide transaction handling
.PP
\fC#include <qsqldatabase.h>\fR
.PP
Inherits QObject.
.PP
.SS "Public Members"
.in +1c
.ti -1c
.BI "\fB~QSqlDatabase\fR ()"
.br
.ti -1c
.BI "bool \fBopen\fR ()"
.br
.ti -1c
.BI "bool \fBopen\fR ( const QString & user, const QString & password )"
.br
.ti -1c
.BI "void \fBclose\fR ()"
.br
.ti -1c
.BI "bool \fBisOpen\fR () const"
.br
.ti -1c
.BI "bool \fBisOpenError\fR () const"
.br
.ti -1c
.BI "QStringList \fBtables\fR () const"
.br
.ti -1c
.BI "QSqlIndex \fBprimaryIndex\fR ( const QString & tablename ) const"
.br
.ti -1c
.BI "QSqlRecord \fBrecord\fR ( const QString & tablename ) const"
.br
.ti -1c
.BI "QSqlRecord \fBrecord\fR ( const QSqlQuery & query ) const"
.br
.ti -1c
.BI "QSqlRecordInfo \fBrecordInfo\fR ( const QString & tablename ) const"
.br
.ti -1c
.BI "QSqlRecordInfo \fBrecordInfo\fR ( const QSqlQuery & query ) const"
.br
.ti -1c
.BI "QSqlQuery \fBexec\fR ( const QString & query = QString::null ) const"
.br
.ti -1c
.BI "QSqlError \fBlastError\fR () const"
.br
.ti -1c
.BI "bool \fBtransaction\fR ()"
.br
.ti -1c
.BI "bool \fBcommit\fR ()"
.br
.ti -1c
.BI "bool \fBrollback\fR ()"
.br
.ti -1c
.BI "virtual void \fBsetDatabaseName\fR ( const QString & name )"
.br
.ti -1c
.BI "virtual void \fBsetUserName\fR ( const QString & name )"
.br
.ti -1c
.BI "virtual void \fBsetPassword\fR ( const QString & password )"
.br
.ti -1c
.BI "virtual void \fBsetHostName\fR ( const QString & host )"
.br
.ti -1c
.BI "virtual void \fBsetPort\fR ( int p )"
.br
.ti -1c
.BI "QString \fBdatabaseName\fR () const"
.br
.ti -1c
.BI "QString \fBuserName\fR () const"
.br
.ti -1c
.BI "QString \fBpassword\fR () const"
.br
.ti -1c
.BI "QString \fBhostName\fR () const"
.br
.ti -1c
.BI "QString \fBdriverName\fR () const"
.br
.ti -1c
.BI "int \fBport\fR () const"
.br
.ti -1c
.BI "QSqlDriver * \fBdriver\fR () const"
.br
.in -1c
.SS "Static Public Members"
.in +1c
.ti -1c
.BI "QSqlDatabase * \fBaddDatabase\fR ( const QString & type, const QString & connectionName = defaultConnection )"
.br
.ti -1c
.BI "QSqlDatabase * \fBdatabase\fR ( const QString & connectionName = defaultConnection, bool open = TRUE )"
.br
.ti -1c
.BI "void \fBremoveDatabase\fR ( const QString & connectionName )"
.br
.ti -1c
.BI "bool \fBcontains\fR ( const QString & connectionName = defaultConnection )"
.br
.ti -1c
.BI "QStringList \fBdrivers\fR ()"
.br
.in -1c
.SS "Properties"
.in +1c
.ti -1c
.BI "QString \fBdatabaseName\fR - the name of the database or the TNS Service Name for the QOCI8 (Oracle) driver"
.br
.ti -1c
.BI "QString \fBhostName\fR - the host name where the database resides"
.br
.ti -1c
.BI "QString \fBpassword\fR - the password used to connect to the database"
.br
.ti -1c
.BI "int \fBport\fR - the port used to connect to the database"
.br
.ti -1c
.BI "QString \fBuserName\fR - the user name connected to the database"
.br
.in -1c
.SS "Protected Members"
.in +1c
.ti -1c
.BI "\fBQSqlDatabase\fR ( const QString & driver, const QString & name, QObject * parent = 0, const char * objname = 0 )"
.br
.in -1c
.SH DESCRIPTION
The QSqlDatabase class is used to create SQL database connections and provide transaction handling.
.PP
This class is used to create connections to SQL databases. It also provides transaction handling functions for those database drivers that support transactions.
.PP
The QSqlDatabase class itself provides an abstract interface for accessing many types of database backend. Database-specific drivers are used internally to actually access and manipulate data, (see QSqlDriver). Result set objects provide the interface for executing and manipulating SQL queries (see QSqlQuery).
.PP
See also Database Classes.
.SH MEMBER FUNCTION DOCUMENTATION
.SH "QSqlDatabase::QSqlDatabase ( const QString & driver, const QString & name, QObject * parent = 0, const char * objname = 0 )\fC [protected]\fR"
Creates a QSqlDatabase connection named \fIname\fR that uses the driver referred to by \fIdriver\fR, with the parent \fIparent\fR and the object name \fIobjname\fR. If the \fIdriver\fR is not recognized, the database connection will have no functionality.
.PP
The currently available drivers are:
.TP
QODBC3 - ODBC (Open Database Connectivity) Driver
.TP
QOCI8 - Oracle Call Interface Driver
.TP
QPSQL7 - PostgreSQL v6.x and v7.x Driver
.TP
QTDS7 - Sybase Adaptive Server and Microsoft SQL Server Driver
.TP
QMYSQL3 - MySQL Driver
.PP
Note that additional 3<sup>rd</sup> party drivers can be loaded dynamically.
.SH "QSqlDatabase::~QSqlDatabase ()"
Destroys the object and frees any allocated resources.
.SH "QSqlDatabase * QSqlDatabase::addDatabase ( const QString & type, const QString & connectionName = defaultConnection )\fC [static]\fR"
Adds a database to the list of database connections using the driver \fItype\fR and the connection name \fIconnectionName\fR.
.PP
The database connection is referred to by \fIconnectionName\fR. A pointer to the newly added database connection is returned. This pointer is owned by QSqlDatabase and will be deleted on program exit or when removeDatabase() is called. If \fIconnectionName\fR is not specified, the newly added database connection becomes the default database connection for the application, and subsequent calls to database() (without a database name parameter) will return a pointer to it.
.PP
See also database() and removeDatabase().
.PP
Examples:
.)l sql/overview/connect1/main.cpp, sql/overview/create_connections/main.cpp and sql/sqltable/main.cpp.
.SH "void QSqlDatabase::close ()"
Closes the database connection, freeing any resources acquired.
.SH "bool QSqlDatabase::commit ()"
Commits a transaction to the database if the driver supports transactions. Returns TRUE if the operation succeeded, FALSE otherwise.
.PP
See also QSqlDriver::hasFeature() and rollback().
.SH "bool QSqlDatabase::contains ( const QString & connectionName = defaultConnection )\fC [static]\fR"
Returns TRUE if the list of database connections contains \fIconnectionName\fR, otherwise returns FALSE.
.SH "QSqlDatabase * QSqlDatabase::database ( const QString & connectionName = defaultConnection, bool open = TRUE )\fC [static]\fR"
Returns a pointer to the database connection named \fIconnectionName\fR. The database connection must have been previously added with database(). If \fIopen\fR is TRUE (the default) and the database connection is not already open it is opened now. If no \fIconnectionName\fR is specified the default connection is used. If \fIconnectionName\fR does not exist in the list of databases, 0 is returned. The pointer returned is owned by QSqlDatabase and should \fInot\fR be deleted.
.PP
Examples:
.)l sql/overview/basicbrowsing/main.cpp and sql/overview/create_connections/main.cpp.
.SH "QString QSqlDatabase::databaseName () const"
Returns the name of the database or the TNS Service Name for the QOCI8 (Oracle) driver. See the "databaseName" property for details.
.SH "QSqlDriver * QSqlDatabase::driver () const"
Returns a pointer to the database driver used to access the database connection.
.SH "QString QSqlDatabase::driverName () const"
Returns the name of the driver used by the database connection.
.SH "QStringList QSqlDatabase::drivers ()\fC [static]\fR"
Returns a list of all available database drivers.
.SH "QSqlQuery QSqlDatabase::exec ( const QString & query = QString::null ) const"
Executes an SQL statement (e.g. an INSERT, UPDATE or DELETE statement) on the database, and returns a QSqlQuery object. Use lastError() to retrieve error information. If \fIquery\fR is QString::null, an empty, invalid query is returned and lastError() is not affected.
.PP
See also QSqlQuery and lastError().
.SH "QString QSqlDatabase::hostName () const"
Returns the host name where the database resides. See the "hostName" property for details.
.SH "bool QSqlDatabase::isOpen () const"
Returns TRUE if the database connection is currently open, otherwise returns FALSE.
.SH "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.
.SH "QSqlError QSqlDatabase::lastError () const"
Returns information about the last error that occurred on the database. See QSqlError for more information.
.PP
Examples:
.)l sql/overview/create_connections/main.cpp and sql/sqltable/main.cpp.
.SH "bool QSqlDatabase::open ()"
Opens the database connection using the current connection values. Returns TRUE on success, and FALSE if there was an error. Error information can be retrieved using the lastError() function.
.PP
See also lastError().
.PP
Examples:
.)l sql/overview/connect1/main.cpp, sql/overview/create_connections/main.cpp and sql/sqltable/main.cpp.
.SH "bool QSqlDatabase::open ( const QString & user, const QString & password )"
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
.PP
Opens the database connection using \fIuser\fR name and \fIpassword\fR. Returns TRUE on success, and FALSE if there was an error. Error information can be retrieved using the lastError() function.
.PP
See also lastError().
.SH "QString QSqlDatabase::password () const"
Returns the password used to connect to the database. See the "password" property for details.
.SH "int QSqlDatabase::port () const"
Returns the port used to connect to the database. See the "port" property for details.
.SH "QSqlIndex QSqlDatabase::primaryIndex ( const QString & tablename ) const"
Returns the primary index for table \fItablename\fR. If no primary index exists an empty QSqlIndex will be returned.
.SH "QSqlRecord QSqlDatabase::record ( const QString & tablename ) const"
Returns a QSqlRecord populated with the names of all the fields in the table (or view) named \fItablename\fR. The order in which the fields are returned is undefined. If no such table (or view) exists, an empty record is returned.
.PP
See also recordInfo().
.SH "QSqlRecord QSqlDatabase::record ( const QSqlQuery & query ) const"
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
.PP
Returns a QSqlRecord populated with the names of all the fields used in the SQL \fIquery\fR. If the query is a "SELECT *" the order in which fields are returned is undefined.
.PP
See also recordInfo().
.SH "QSqlRecordInfo QSqlDatabase::recordInfo ( const QString & tablename ) const"
Returns a QSqlRecordInfo populated with meta-data about the table (or view) \fItablename\fR. If no such table (or view) exists, an empty record is returned.
.PP
See also QSqlRecordInfo, QSqlFieldInfo and record().
.SH "QSqlRecordInfo QSqlDatabase::recordInfo ( const QSqlQuery & query ) const"
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
.PP
Returns a QSqlRecordInfo object with meta data for the QSqlQuery \fIquery\fR. Note that this overloaded function may return not as much information as the recordInfo function which takes the name of a table as parameter.
.PP
See also QSqlRecordInfo, QSqlFieldInfo and record().
.SH "void QSqlDatabase::removeDatabase ( const QString & connectionName )\fC [static]\fR"
Removes the database connection \fIconnectionName\fR from the list of database connections. Note that there should be no open queries on the database connection when this function is called, otherwise a resource leak will occur.
.SH "bool QSqlDatabase::rollback ()"
Rolls a transaction back on the database if the driver supports transactions. Returns TRUE if the operation succeeded, FALSE otherwise.
.PP
See also QSqlDriver::hasFeature(), commit() and transaction().
.SH "void QSqlDatabase::setDatabaseName ( const QString & name )\fC [virtual]\fR"
Sets the name of the database or the TNS Service Name for the QOCI8 (Oracle) driver to \fIname\fR. See the "databaseName" property for details.
.SH "void QSqlDatabase::setHostName ( const QString & host )\fC [virtual]\fR"
Sets the host name where the database resides to \fIhost\fR. See the "hostName" property for details.
.SH "void QSqlDatabase::setPassword ( const QString & password )\fC [virtual]\fR"
Sets the password used to connect to the database to \fIpassword\fR. See the "password" property for details.
.SH "void QSqlDatabase::setPort ( int p )\fC [virtual]\fR"
Sets the port used to connect to the database to \fIp\fR. See the "port" property for details.
.SH "void QSqlDatabase::setUserName ( const QString & name )\fC [virtual]\fR"
Sets the user name connected to the database to \fIname\fR. See the "userName" property for details.
.SH "QStringList QSqlDatabase::tables () const"
Returns a list of tables in the database.
.SH "bool QSqlDatabase::transaction ()"
Begins a transaction on the database if the driver supports transactions. Returns TRUE if the operation succeeded, FALSE otherwise.
.PP
See also QSqlDriver::hasFeature(), commit() and rollback().
.SH "QString QSqlDatabase::userName () const"
Returns the user name connected to the database. See the "userName" property for details.
.SS "Property Documentation"
.SH "QString databaseName"
This property holds the name of the database or the TNS Service Name for the QOCI8 (Oracle) driver.
.PP
Set this property's value with setDatabaseName() and get this property's value with databaseName().
.SH "QString hostName"
This property holds the host name where the database resides.
.PP
Set this property's value with setHostName() and get this property's value with hostName().
.SH "QString password"
This property holds the password used to connect to the database.
.PP
Set this property's value with setPassword() and get this property's value with password().
.SH "int port"
This property holds the port used to connect to the database.
.PP
Set this property's value with setPort() and get this property's value with port().
.SH "QString userName"
This property holds the user name connected to the database.
.PP
Set this property's value with setUserName() and get this property's value with userName().

.SH "SEE ALSO"
.BR http://doc.trolltech.com/qsqldatabase.html
.BR http://www.trolltech.com/faq/tech.html
.SH COPYRIGHT
Copyright 1992-2001 Trolltech AS, http://www.trolltech.com.  See the
license file included in the distribution for a complete license
statement.
.SH AUTHOR
Generated automatically from the source code.
.SH BUGS
If you find a bug in Qt, please report it as described in
.BR http://doc.trolltech.com/bughowto.html .
Good bug reports help us to help you. Thank you.
.P
The definitive Qt documentation is provided in HTML format; it is
located at $QTDIR/doc/html and can be read using Qt Assistant or with
a web browser. This man page is provided as a convenience for those
users who prefer man pages, although this format is not officially
supported by Trolltech. 
.P
If you find errors in this manual page, please report them to
.BR [e-mail] .
Please include the name of the manual page (qsqldatabase.3qt) and the Qt
version (3.0.0).