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authorCasper van Donderen <casper.vandonderen@nokia.com>2012-04-27 15:18:27 +0200
committerQt by Nokia <qt-info@nokia.com>2012-04-28 13:53:46 +0200
commit00b961c37f82977615ab9c4d03e185229cc55154 (patch)
treebc9012d3ac08c19f2a66b5733dd8450506742243 /doc/src/sql/sql-programming/sql-driver.qdoc
parent82fa92b23cca834481571f0b0a5d66bc33a672e9 (diff)
Doc: Fix most qdoc errors in QtSql.
- Move 2 images from qtdoc. - Add "make docs" command for qtsql - Fix qdoc command usage errors. Change-Id: Id2f0548d09ed8f77b2317863d443c19d1cccdd83 Reviewed-by: Lars Knoll <lars.knoll@nokia.com>
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-/****************************************************************************
-**
-** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
-** Contact: http://www.qt-project.org/
-**
-** This file is part of the documentation of the Qt Toolkit.
-**
-** $QT_BEGIN_LICENSE:FDL$
-** GNU Free Documentation License
-** Alternatively, this file may be used under the terms of the GNU Free
-** Documentation License version 1.3 as published by the Free Software
-** Foundation and appearing in the file included in the packaging of
-** this file.
-**
-** Other Usage
-** Alternatively, this file may be used in accordance with the terms
-** and conditions contained in a signed written agreement between you
-** and Nokia.
-**
-**
-**
-**
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-/*!
- \page sql-driver.html
- \title SQL Database Drivers
- \brief How to configure and install Qt SQL drivers for supported databases.
-
- \ingroup qt-sql
-
- The Qt SQL module uses driver \l{How to Create Qt
- Plugins}{plugins} to communicate with the different database
- APIs. Since Qt's SQL Module API is database-independent, all
- database-specific code is contained within these drivers. Several
- drivers are supplied with Qt and other drivers can be added. The
- driver source code is supplied and can be used as a model for
- \l{#development}{writing your own drivers}.
-
- \tableofcontents
-
- \section1 Supported Databases
-
- The table below lists the drivers included with Qt. Due to
- license incompatibilities with the GPL, not all of the plugins
- are provided with Open Source Versions of Qt.
-
- \table
- \header \li Driver name \li DBMS
- \row \li \link #QDB2 QDB2\endlink \li IBM DB2 (version 7.1 and above)
- \row \li \link #QIBASE QIBASE\endlink \li Borland InterBase
- \row \li \link #QMYSQL QMYSQL\endlink \li MySQL
- \row \li \link #QOCI QOCI\endlink \li Oracle Call Interface Driver
- \row \li \link #QODBC QODBC\endlink
- \li Open Database Connectivity (ODBC) - Microsoft SQL Server and other
- ODBC-compliant databases
- \row \li \link #QPSQL QPSQL\endlink \li PostgreSQL (versions 7.3 and above)
- \row \li \link #QSQLITE2 QSQLITE2\endlink \li SQLite version 2
- \row \li \link #QSQLITE QSQLITE\endlink \li SQLite version 3
- \row \li \link #QTDS QTDS\endlink \li Sybase Adaptive Server \note obsolete from Qt 4.7
- \endtable
-
- SQLite is the in-process database system with the best test coverage
- and support on all platforms. Oracle via OCI, and PostreSQL and MySQL
- through either ODBC or a native driver are well-tested on Windows and
- Linux. The completeness of the support for other systems depends on the
- availability and quality of client libraries.
-
- \b{Note:} To build a driver plugin you need to have the appropriate
- client library for your Database Management System (DBMS). This provides
- access to the API exposed by the DBMS, and is typically shipped with it.
- Most installation programs also allow you to install "development
- libraries", and these are what you need. These libraries are responsible
- for the low-level communication with the DBMS.
-
- \target building
- \section1 Building the Drivers Using Configure
-
- On Unix and Mac OS X, the Qt \c configure script tries to
- automatically detect the available client libraries on your
- machine. Run \c{configure -help} to see what drivers can be
- built. You should get an output similar to this:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 0
-
- The \c configure script cannot detect the necessary libraries
- and include files if they are not in the standard paths, so it
- may be necessary to specify these paths using the \c -I and \c -L
- command-line options. For example, if your MySQL include files
- are installed in \c /usr/local/mysql (or in \c{C:\mysql\include}
- on Windows), then pass the following parameter to configure: \c
- -I/usr/local/mysql (or \c{-I C:\mysql\include} for Windows).
-
- On Windows the \c -I parameter doesn't accept spaces in
- filenames, so use the 8.3 name instead; for example, use
- \c{C:\progra~1\mysql} instead of \c{C:\Program Files\mysql}.
-
- Use the \c{-qt-sql-<driver>} parameter to build the database driver
- statically into your Qt library or \c{-plugin-sql-<driver>} to build
- the driver as a plugin. Look at the sections that follow for
- additional information about required libraries.
-
- \target buildingmanually
- \section1 Building the Plugins Manually
-
- \target QMYSQL
- \section2 QMYSQL for MySQL 4 and higher
-
- \section3 QMYSQL Stored Procedure Support
-
- MySQL 5 introduces stored procedure support at the SQL level, but no
- API to control IN, OUT and INOUT parameters. Therefore, parameters
- have to be set and read using SQL commands instead of QSqlQuery::bindValue().
-
- Example stored procedure:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 1
-
- Source code to access the OUT values:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.cpp 2
-
- \b{Note:} \c{@outval1} and \c{@outval2} are variables local to the current
- connection and will not be affected by queries sent from another host
- or connection.
-
- \section3 Embedded MySQL Server
-
- The MySQL embedded server is a drop-in replacement for the normal
- client library. With the embedded MySQL server, a MySQL server is
- not required to use MySQL functionality.
-
- To use the embedded MySQL server, simply link the Qt plugin to \c
- libmysqld instead of libmysqlclient. This can be done by replacing
- \c -lmysqlclient_r by \c -lmysqld in the \c qmake command in the
- section below.
-
- Please refer to the MySQL documentation, chapter "libmysqld, the Embedded
- MySQL Server Library" for more information about the MySQL embedded server.
-
- \section3 How to Build the QMYSQL Plugin on Unix and Mac OS X
-
- You need the MySQL header files and as well as the shared library
- \c{libmysqlclient.so}. Depending on your Linux distribution you may
- need to install a package which is usually called "mysql-devel".
-
- Tell \l qmake where to find the MySQL header files and shared
- libraries (here it is assumed that MySQL is installed in
- \c{/usr/local}) and run \c{make}:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 3
-
- After installing Qt, as described in the \l{Installing Qt for X11
- Platforms} document, you also need to install the plugin in the
- standard location:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 4
-
- \section3 How to Build the QMYSQL Plugin on Windows
-
- You need to get the MySQL installation files. Run \c SETUP.EXE and
- choose "Custom Install". Install the "Libs & Include Files" Module.
- Build the plugin as follows (here it is assumed that MySQL is
- installed in \c{C:\MySQL}):
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 5
-
- If you are not using a Microsoft compiler, replace \c nmake with \c
- make in the line above.
-
- \note This database plugin is not supported for Windows CE.
-
- \note Including \c{"-o Makefile"} as an argument to \l qmake to
- tell it where to build the makefile can cause the plugin to be
- built in release mode only. If you are expecting a debug version
- to be built as well, don't use the \c{"-o Makefile"} option.
-
- \section3 How to build the MySQL driver for MinGW users
-
- The following steps have been used successfully for WinXP SP3. In
- this example, Qt 4.6.2 is shown.
-
- \list
-
- \li Download the following components:
- \list
- \li \c{MinGW-5.1.6.exe}
- \li \c{mingw-utils-0.3.tar.gz}
- \li Qt sources, e.g. \c{qt-everywhere-opensource-src-4.6.2.zip}
- \li \c{mysql-5.1.35-win32.msi}
- \endlist
-
- \li Install \c{MinGW-5.1.6.exe} in, e.g. \c{C:\MinGW}.
-
- \li Extract \c{mingw-utils-0.3.tar.gz} into, e.g. \c{C:\MinGW}.
-
- \li Add the path for \c{MinGW-5.1.6.exe} to your \c{PATH} variable,
- e.g. \c{C:\MinGW\bin;}
-
- \li Extract the Qt sources, (\c{qt-everywhere-opensource-src-4.6.2.zip}),
- into, e.g. \c{C:\Qt}.
-
- \li Add the path for the eventual Qt binary to your \c{PATH} variable,
- e.g. \c{C:\Qt\4.6.2\bin;}.
-
- \li Install MySQL (\c{mysql-5.1.35-win32.msi}), customizing the
- components. Select only the headers and libraries. Install in,
- e.g. \c{C:\MySQL\MySQL51}.
-
- \li Open the DOS prompt, go to \c{C:\MySQL\MySQL51\lib\opt}, and run
- the following commands:
- \list
- \li \c{reimp -d libmysql.lib}
- \li \c{dlltool -k -d libmysql.def -l libmysql.a}
- \endlist
-
- \li Open the DOS prompt, go to \c{C:\Qt\4.6.2} and run the following commands:
- \list
- \li \c{configure.exe -debug-and-release -platform win32-g++ -qt-sql-mysql
- -l mysql -I C:\MySQL\MySQL51\include -L C:\MySQL\MySQL51\lib\opt}
- \li \c{mingw32-make sub-src}
- \endlist
- This step takes a long time.
-
- \li Open the DOS prompt, go to
- \c{C:\Qt\4.6.2\src\plugins\sqldrivers\mysql} and run the
- following command:
- \list
- \li \c{qmake "INCLUDEPATH+=C:\MySQL\MySQL51\include" "LIBS+=-L. mysql" mysql.pro}
- \endlist
-
- \li Now the following libraries are ready in \c{C:\Qt\4.6.2\plugins\sqldrivers}.
- \list
- \li \c{libqsqlmysql4.a}
- \li \c{libqsqlmysqld4.a}
- \li \c{qsqlmysql4.dll}
- \li \c{qsqlmysqld4.dll}
- \endlist
- To use the SDK and QtCreator directly, copy these libraries to
- your \c{C:\Qt\...\qt\plugins\sqldrivers\}, and copy
- \c{C:\MySQL\MySQL51\lib\opt\libmysql.dll} to your \c{C:\Qt\...\qt\bin\}.
-
- \endlist
-
- \target QOCI
- \section2 QOCI for the Oracle Call Interface (OCI)
-
- \section3 General Information about the OCI plugin
-
- The Qt OCI plugin supports Oracle 9i, 10g and higher. After
- connecting to the Oracle server, the plugin will auto-detect the
- database version and enable features accordingly.
-
- It's possible to connect to a Oracle database without a tnsnames.ora file.
- This requires that the database SID is passed to the driver as the database
- name and that a hostname is given.
-
- \section3 OCI User Authentication
-
- The Qt OCI plugin supports authentication using
- external credentials (OCI_CRED_EXT). Usually, this means that the database
- server will use the user authentication provided by the operating system
- instead of its own authentication mechanism.
-
- Leave the username and password empty when opening a connection with
- QSqlDatabase to use the external credentials authentication.
-
- \section3 OCI BLOB/LOB Support
-
- Binary Large Objects (BLOBs) can be read and written, but be aware
- that this process may require a lot of memory. You should use a forward
- only query to select LOB fields (see QSqlQuery::setForwardOnly()).
-
- Inserting BLOBs should be done using either a prepared query where the
- BLOBs are bound to placeholders or QSqlTableModel, which uses a prepared
- query to do this internally.
-
- \section3 How to Build the OCI Plugin on Unix and Mac OS X
-
- For Oracle 10g, all you need is the "Instant Client Package - Basic" and
- "Instant Client Package - SDK". For Oracle prior to 10g, you require
- the standard Oracle client and the SDK packages.
-
- Oracle library files required to build the driver:
-
- \list
- \li \c libclntsh.so (all versions)
- \li \c libwtc9.so (only Oracle 9)
- \endlist
-
- Tell \c qmake where to find the Oracle header files and shared
- libraries and run make:
-
- For Oracle version 9:
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 6
-
- For Oracle version 10, we assume that you installed the RPM packages of the
- Instant Client Package SDK (you need to adjust the version number accordingly):
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 7
-
- \b{Note:} If you are using the Oracle Instant Client package,
- you will need to set LD_LIBRARY_PATH when building the OCI SQL plugin
- and when running an application that uses the OCI SQL plugin. You can
- avoid this requirement by setting and RPATH and listing all of the
- libraries to link to. Here is an example:
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 32
-
- If you wish to build the OCI plugin manually with this method the procedure looks like this:
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 33
-
- \section3 How to Build the OCI Plugin on Windows
-
- Choosing the option "Programmer" in the Oracle Client Installer from
- the Oracle Client Installation CD is generally sufficient to build the
- plugin. For some versions of Oracle Client, you may also need to select
- the "Call Interface (OCI)" option if it is available.
-
- Build the plugin as follows (here it is assumed that Oracle Client is
- installed in \c{C:\oracle}):
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 8
-
- If you are not using a Microsoft compiler, replace \c nmake with \c
- make in the line above.
-
- When you run your application you will also need to add the \c oci.dll
- path to your \c PATH environment variable:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 9
-
- \b{Note:} This database plugin is not supported for Windows CE.
-
- \target QODBC
- \section2 QODBC for Open Database Connectivity (ODBC)
-
- \section3 General Information about the ODBC plugin
-
- ODBC is a general interface that allows you to connect to multiple
- DBMSs using a common interface. The QODBC driver allows you to connect
- to an ODBC driver manager and access the available data sources. Note
- that you also need to install and configure ODBC drivers for the ODBC
- driver manager that is installed on your system. The QODBC plugin
- then allows you to use these data sources in your Qt applications.
-
- \b{Note:} You should use native drivers in preference to the ODBC
- driver where they are available. ODBC support can be used as a fallback
- for compliant databases if no native drivers are available.
-
- On Windows an ODBC driver manager should be installed by default.
- For Unix systems there are some implementations which must be
- installed first. Note that every client that uses your application is
- required to have an ODBC driver manager installed, otherwise the
- QODBC plugin will not work.
-
- Be aware that when connecting to an ODBC datasource you must pass in
- the name of the ODBC datasource to the QSqlDatabase::setDatabaseName()
- function rather than the actual database name.
-
- The QODBC Plugin needs an ODBC compliant driver manager version 2.0 or
- later to work. Some ODBC drivers claim to be version 2.0 compliant,
- but do not offer all the necessary functionality. The QODBC plugin
- therefore checks whether the data source can be used after a
- connection has been established and refuses to work if the check
- fails. If you don't like this behavior, you can remove the \c{#define
- ODBC_CHECK_DRIVER} line from the file \c{qsql_odbc.cpp}. Do this at
- your own risk!
-
- By default, Qt instructs the ODBC driver to behave as an ODBC 2.x
- driver. However, for some \e{driver-manager/ODBC 3.x-driver}
- combinations (e.g., \e{unixODBC/MaxDB ODBC}), telling the ODBC
- driver to behave as a 2.x driver can cause the driver plugin to
- have unexpected behavior. To avoid this problem, instruct the ODBC
- driver to behave as a 3.x driver by
- \l{QSqlDatabase::setConnectOptions()} {setting the connect option}
- \c{"SQL_ATTR_ODBC_VERSION=SQL_OV_ODBC3"} before you
- \l{QSqlDatabase::open()} {open your database connection}. Note
- that this will affect multiple aspects of ODBC driver behavior,
- e.g., the SQLSTATEs. Before setting this connect option, consult
- your ODBC documentation about behavior differences you can expect.
-
- If you experience very slow access of the ODBC datasource, make sure
- that ODBC call tracing is turned off in the ODBC datasource manager.
-
- Some drivers don't support scrollable cursors. In that case case only
- queries in forwardOnly mode can be used successfully.
-
- \section3 ODBC Stored Procedure Support
-
- With Microsoft SQL Server the result set returned by a stored
- procedure that uses the return statement, or returns multiple result
- sets, will be accessible only if you set the query's forward only
- mode to \e forward using \l QSqlQuery::setForwardOnly().
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.cpp 10
-
- \b{Note:} The value returned by the stored procedure's return statement
- is discarded.
-
- \section3 ODBC Unicode Support
-
- The QODBC Plugin will use the Unicode API if UNICODE is defined. On
- Windows NT based systems, this is the default. Note that the ODBC
- driver and the DBMS must also support Unicode.
-
- Some driver managers and drivers don't support UNICODE. To use the
- QODBC plugin with such drivers it has to be compiled with the
- Q_ODBC_VERSION_2 defined.
-
- For the Oracle 9 ODBC driver (Windows), it is necessary to check
- "SQL_WCHAR support" in the ODBC driver manager otherwise Oracle
- will convert all Unicode strings to local 8-bit.
-
- \section3 How to Build the ODBC Plugin on Unix and Mac OS X
-
- It is recommended that you use unixODBC. You can find the latest
- version and ODBC drivers at \l http://www.unixodbc.org.
- You need the unixODBC header files and shared libraries.
-
- Tell \c qmake where to find the unixODBC header files and shared
- libraries (here it is assumed that unixODBC is installed in
- \c{/usr/local/unixODBC}) and run \c{make}:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 11
-
- \section3 How to Build the ODBC Plugin on Windows
-
- The ODBC header and include files should already be installed in the
- right directories. You just have to build the plugin as follows:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 12
-
- If you are not using a Microsoft compiler, replace \c nmake with \c
- make in the line above.
-
- \b{Note:} This database plugin is not officially supported for Windows CE.
-
- \target QPSQL
- \section2 QPSQL for PostgreSQL (Version 7.3 and Above)
-
- \section3 General Information about the QPSQL driver
-
- The QPSQL driver supports version 7.3 and higher of the PostgreSQL server.
- We recommend that you use a client library from version 7.3.15, 7.4.13,
- 8.0.8, 8.1.4 or more recent as these versions contain security fixes, and
- as the QPSQL driver might not build with older versions of the client
- library depending on your platform.
-
- For more information about PostgreSQL visit \l http://www.postgresql.org.
-
- \section3 QPSQL Unicode Support
-
- The QPSQL driver automatically detects whether the PostgreSQL
- database you are connecting to supports Unicode or not. Unicode is
- automatically used if the server supports it. Note that the driver
- only supports the UTF-8 encoding. If your database uses any other
- encoding, the server must be compiled with Unicode conversion
- support.
-
- Unicode support was introduced in PostgreSQL version 7.1 and it will
- only work if both the server and the client library have been compiled
- with multibyte support. More information about how to set up a
- multibyte enabled PostgreSQL server can be found in the PostgreSQL
- Administrator Guide, Chapter 5.
-
- \section3 QPSQL BLOB Support
-
- Binary Large Objects are supported through the \c BYTEA field type in
- PostgreSQL server versions >= 7.1.
-
- \section3 How to Build the QPSQL Plugin on Unix and Mac OS X
-
- You need the PostgreSQL client library and headers installed.
-
- To make \c qmake find the PostgreSQL header files and shared
- libraries, run \c qmake the following way (assuming that the
- PostgreSQL client is installed in \c{/usr}):
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 13
-
- After installing Qt, as described in the \l{Installing Qt for X11 Platforms} document,
- you also need to install the plugin in the standard location:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 14
-
- \section3 How to Build the QPSQL Plugin on Windows
-
- Install the appropriate PostgreSQL developer libraries for your
- compiler. Assuming that PostgreSQL was installed in \c{C:\psql},
- build the plugin as follows:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 15
-
- Users of MinGW may wish to consult the following online document:
- \l{PostgreSQL MinGW/Native Windows}.
-
- \b{Note:} This database plugin is not supported for Windows CE.
-
- \target QTDS
- \section2 QTDS for Sybase Adaptive Server
-
- \note TDS is no longer used by MS Sql Server, and is superceded by
- \l{QODBC}{ODBC}. QTDS is obsolete from Qt 4.7.
-
- \section3 General Information about QTDS
-
- It is not possible to set the port with QSqlDatabase::setPort() due to limitations in the
- Sybase client library. Refer to the Sybase documentation for information on how to set up
- a Sybase client configuration file to enable connections to databases on non-default ports.
-
- \section3 How to Build the QTDS Plugin on Unix and Mac OS X
-
- Under Unix, two libraries are available which support the TDS protocol:
-
- \list
- \li FreeTDS, a free implementation of the TDS protocol
- (\l{http://www.freetds.org}). Note that FreeTDS is not yet stable,
- so some functionality may not work as expected.
-
- \li Sybase Open Client, available from \l{http://www.sybase.com}.
- Note for Linux users: Get the Open Client RPM from
- \l{http://linux.sybase.com}.
- \endlist
-
- Regardless of which library you use, the shared object file
- \c{libsybdb.so} is needed. Set the \c SYBASE environment variable to
- point to the directory where you installed the client library and
- execute \c{qmake}:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 16
-
- \section3 How to Build the QDTS Plugin on Windows
-
- You can either use the DB-Library supplied by Microsoft or the Sybase
- Open Client (\l{http://www.sybase.com}). You must include \c
- NTWDBLIB.LIB to build the plugin:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 17
-
- By default the Microsoft library is used on Windows, if you want to
- force the use of the Sybase Open Client, you must define \c
- Q_USE_SYBASE in \c{%QTDIR%\src\sql\drivers\tds\qsql_tds.cpp}. If you
- are not using a Microsoft compiler, replace \c nmake with \c make in
- the line above.
-
- \b{Note:} This database plugin is not supported for Windows CE.
-
- \target QDB2
- \section2 QDB2 for IBM DB2 (Version 7.1 and Above)
-
- \section3 General Information about QDB2
-
- The Qt DB2 plugin makes it possible to access IBM DB2 databases. It
- has been tested with IBM DB2 v7.1 and 7.2. You must install the IBM
- DB2 development client library, which contains the header and library
- files necessary for compiling the QDB2 plugin.
-
- The QDB2 driver supports prepared queries, reading/writing of Unicode
- strings and reading/writing of BLOBs.
-
- We suggest using a forward-only query when calling stored procedures
- in DB2 (see QSqlQuery::setForwardOnly()).
-
- \section3 How to Build the QDB2 Plugin on Unix and Mac OS X
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 18
-
- After installing Qt, as described in the \l{Installing Qt for X11 Platforms} document,
- you also need to install the plugin in the standard location:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 19
-
- \section3 How to Build the QDB2 Plugin on Windows
-
- The DB2 header and include files should already be installed in the
- right directories. You just have to build the plugin as follows:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 20
-
- If you are not using a Microsoft compiler, replace \c nmake
- with \c make in the line above.
-
- \b{Note:} This database plugin is not supported for Windows CE.
-
- \target QSQLITE2
- \section2 QSQLITE2 for SQLite Version 2
-
- The Qt SQLite 2 plugin is offered for compatibility. Whenever
- possible, use the \l{#QSQLITE}{version 3 plugin} instead. The
- build instructions for version 3 apply to version 2 as well.
-
- \target QSQLITE
- \section2 QSQLITE for SQLite (Version 3 and Above)
-
- \section3 General Information about QSQLITE
-
- The Qt SQLite plugin makes it possible to access SQLite
- databases. SQLite is an in-process database, which means that it
- is not necessary to have a database server. SQLite operates on a
- single file, which must be set as the database name when opening
- a connection. If the file does not exist, SQLite will try to
- create it. SQLite also supports in-memory databases, simply pass
- ":memory:" as the database name.
-
- SQLite has some restrictions regarding multiple users and
- multiple transactions. If you try to read/write on a resource from different
- transactions, your application might freeze until one transaction commits
- or rolls back. The Qt SQLite driver will retry to write to a locked resource
- until it runs into a timeout (see \c{QSQLITE_BUSY_TIMEOUT}
- at QSqlDatabase::setConnectOptions()).
-
- In SQLite any column, with the exception of an INTEGER PRIMARY KEY column,
- may be used to store any type of value. For instance, a column declared as
- INTEGER may contain an integer value in one row and a text value in the
- next. This is due to SQLite associating the type of a value with the value
- itself rather than with the column it is stored in. A consequence of this
- is that the type returned by QSqlField::type() only indicates the field's
- recommended type. No assumption of the actual type should be made from
- this and the type of the individual values should be checked.
-
- The driver is locked for updates while a select is executed. This
- may cause problems when using QSqlTableModel because Qt's item views
- fetch data as needed (with QSqlQuery::fetchMore() in the case of
- QSqlTableModel).
-
- You can find information about SQLite on \l{http://www.sqlite.org}.
-
- \section3 How to Build the QSQLITE Plugin
-
- SQLite version 3 is included as a third-party library within Qt.
- It can be built by passing the following parameters to the
- configure script: \c{-plugin-sql-sqlite} (build as a plugin) or
- \c{-qt-sql-sqlite} (linked directly into the Qt library).
-
- If you don't want to use the SQLite library included with Qt, you
- can pass \c{-system-sqlite} to the configure script to use sqlite
- libraries in the operating system. Alternatively, you can build
- it manually (replace \c $SQLITE with the directory where
- SQLite resides):
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 21
-
- After installing Qt, as described in the \l{Installing Qt for X11 Platforms} document,
- you also need to install the plugin in the standard location:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 22
-
- On Windows:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 23
-
- \section3 QSQLITE File Format Compatibility
-
- SQLite minor releases sometimes break file format forward compatibility.
- For example, SQLite 3.3 can read database files created with SQLite 3.2,
- but databases created with SQLite 3.3 cannot be read by SQLite 3.2.
- Please refer to the SQLite documentation and change logs for information about
- file format compatibility between versions.
-
- Qt minor releases usually follow the SQLite minor releases, while Qt patch releases
- follow SQLite patch releases. Patch releases are therefore both backward and forward
- compatible.
-
- To force SQLite to use a specific file format, it is necessary to build and
- ship your own database plugin with your own SQLite library as illustrated above.
- Some versions of SQLite can be forced to write a specific file format by setting
- the \c{SQLITE_DEFAULT_FILE_FORMAT} define when building SQLite.
-
- \target QIBASE
- \section2 QIBASE for Borland InterBase
-
- \section3 General Information about QIBASE
-
- The Qt InterBase plugin makes it possible to access the InterBase and
- Firebird databases. InterBase can either be used as a client/server or
- without a server in which case it operates on local files. The
- database file must exist before a connection can be established. Firebird
- must be used with a server configuration.
-
- Note that InterBase requires you to specify the full path to the
- database file, no matter whether it is stored locally or on another
- server.
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.cpp 24
-
- You need the InterBase/Firebird development headers and libraries
- to build this plugin.
-
- Due to license incompatibilities with the GPL, users of the Qt Open Source
- Edition are not allowed to link this plugin to the commercial editions of
- InterBase. Please use Firebird or the free edition of InterBase.
-
- \section3 QIBASE Unicode Support and Text Encoding
-
- By default the driver connects to the database using UNICODE_FSS. This can
- be overridden by setting the ISC_DPB_LC_CTYPE parameter with
- QSqlDatabase::setConnectOptions() before opening the connection.
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.cpp 25
-
- If Qt doesn't support the given text encoding the driver will issue a
- warning message and connect to the database using UNICODE_FSS.
-
- Note that if the text encoding set when connecting to the database is
- not the same as in the database, problems with transliteration might arise.
-
- \section3 QIBASE Stored procedures
-
- InterBase/Firebird return OUT values as result set, so when calling stored
- procedure, only IN values need to be bound via QSqlQuery::bindValue(). The
- RETURN/OUT values can be retrieved via QSqlQuery::value(). Example:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.cpp 26
-
- \section3 How to Build the QIBASE Plugin on Unix and Mac OS X
-
- The following assumes InterBase or Firebird is installed in
- \c{/opt/interbase}:
-
- If you are using InterBase:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 27
-
- If you are using Firebird, the Firebird library has to be set explicitly:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 28
-
- \section3 How to Build the QIBASE Plugin on Windows
-
- The following assumes InterBase or Firebird is installed in
- \c{C:\interbase}:
-
- If you are using InterBase:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 29
-
- If you are using Firebird, the Firebird library has to be set explicitly:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.qdoc 30
-
- If you are not using a Microsoft compiler, replace \c nmake
- with \c make in the line above.
-
- Note that \c{C:\interbase\bin} must be in the \c PATH.
-
- \b{Note:} This database plugin is not supported for Windows CE.
-
- \target troubleshooting
- \section1 Troubleshooting
-
- You should always use client libraries that have been compiled with
- the same compiler as you are using for your project. If you cannot get
- a source distibution to compile the client libraries yourself, you
- must make sure that the pre-compiled library is compatible with
- your compiler, otherwise you will get a lot of "undefined symbols"
- errors. Some compilers have tools to convert libraries, e.g. Borland
- ships the tool \c{COFF2OMF.EXE} to convert libraries that have been
- generated with Microsoft Visual C++.
-
- If the compilation of a plugin succeeds but it cannot be loaded,
- make sure that the following requirements are met:
-
- \list
- \li Ensure that you are using a shared Qt library; you cannot use the
- plugins with a static build.
- \li Ensure that the plugin is in the correct directory. You can use
- QApplication::libraryPaths() to determine where Qt looks for plugins.
- \li Ensure that the client libraries of the DBMS are available on the
- system. On Unix, run the command \c{ldd} and pass the name of the
- plugin as parameter, for example \c{ldd libqsqlmysql.so}. You will
- get a warning if any of the client libraries couldn't be found.
- On Windows, you can use Visual Studio's dependency walker.
- \li Compile Qt with \c{QT_DEBUG_COMPONENT} defined to get very verbose
- debug output when loading plugins.
- \endlist
-
- Make sure you have followed the guide to \l{Deploying Plugins}.
- If you experience plugin load problems and see output like this:
-
- \snippet doc/src/snippets/code/doc_src_sql-driver.cpp 31
-
- the problem is usually that the plugin had the wrong \l{Deploying
- Plugins#The Build Key}{build key}. This might require removing an
- entry from the \l{Deploying Plugins#The Plugin Cache} {plugin cache}.
-
- \target development
- \section1 How to Write Your Own Database Driver
-
- QSqlDatabase is responsible for loading and managing database driver
- plugins. When a database is added (see QSqlDatabase::addDatabase()),
- the appropriate driver plugin is loaded (using QSqlDriverPlugin).
- QSqlDatabase relies on the driver plugin to provide interfaces for
- QSqlDriver and QSqlResult.
-
- QSqlDriver is an abstract base class which defines the functionality
- of a SQL database driver. This includes functions such as
- QSqlDriver::open() and QSqlDriver::close(). QSqlDriver is responsible
- for connecting to a database, establish the proper environment, etc.
- In addition, QSqlDriver can create QSqlQuery objects appropriate for
- the particular database API. QSqlDatabase forwards many of its
- function calls directly to QSqlDriver which provides the concrete
- implementation.
-
- QSqlResult is an abstract base class which defines the functionality
- of a SQL database query. This includes statements such as \c{SELECT},
- \c{UPDATE}, and \c{ALTER} \c{TABLE}. QSqlResult contains functions
- such as QSqlResult::next() and QSqlResult::value(). QSqlResult is
- responsible for sending queries to the database, returning result
- data, etc. QSqlQuery forwards many of its function calls directly to
- QSqlResult which provides the concrete implementation.
-
- QSqlDriver and QSqlResult are closely connected. When implementing a
- Qt SQL driver, both of these classes must to be subclassed and the
- abstract virtual methods in each class must be implemented.
-
- To implement a Qt SQL driver as a plugin (so that it is
- recognized and loaded by the Qt library at runtime), the driver
- must use the Q_EXPORT_PLUGIN2() macro. Read \l{How to Create Qt
- Plugins} for more information on this. You can also check out how
- this is done in the SQL plugins that are provided with Qt in
- \c{QTDIR/src/plugins/sqldrivers} and \c{QTDIR/src/sql/drivers}.
-
- The following code can be used as a skeleton for a SQL driver:
-
- \snippet doc/src/snippets/sqldatabase/sqldatabase.cpp 47
- \codeline
- \snippet doc/src/snippets/sqldatabase/sqldatabase.cpp 48
-*/