ODBC and DB2 Functions (PDO_ODBC)

简介

PDO_ODBC is a driver that implements the PHP Data Objects (PDO) interface to enable access from PHP to databases through ODBC drivers or through the IBM DB2 Call Level Interface (DB2 CLI) library. PDO_ODBC currently supports three different "flavours" of database drivers:

ibm-db2

Supports access to IBM DB2 Universal Database, Cloudscape, and Apache Derby servers through the free DB2 express-C client.

unixODBC

Supports access to database servers through the unixODBC driver manager and the database's own ODBC drivers.

generic

Offers a compile option for ODBC driver managers that are not explicitly supported by PDO_ODBC.

On Windows, php_pdo_odbc.dll has to be enabled as extension in php.ini. It is linked against the Windows ODBC Driver Manager so that PHP can connect to any database cataloged as a System DSN, and is the recommended driver for connecting to Microsoft SQL Server databases.

安装

PDO_ODBC on UNIX systems

  1. PDO_ODBC is included in the PHP source. You can compile the PDO_ODBC extension as either a static or shared module using the following configure commands.

    ibm_db2

    ./configure --with-pdo-odbc=ibm-db2,/opt/IBM/db2/V8.1/
    To build PDO_ODBC with the ibm-db2 flavour, you have to have previously installed the DB2 application development headers on the same machine on which you are compiling PDO_ODBC. The DB2 application development headers are an installable option in the DB2 servers, and are also available as part of the DB2 Application Development Client freely available for download from the IBM developerWorks » website.

    If you do not supply a location for the DB2 libraries and headers to the configure command, PDO_ODBC defaults to /home/db2inst1/sqllib.

    unixODBC

    ./configure --with-pdo-odbc=unixODBC,/usr/local
    If you do not supply a location for the unixODBC libraries and headers to the configure command, PDO_ODBC defaults to /usr/local.

    generic
    ./configure --with-pdo-odbc=generic,/usr/local,libname,ldflags,cflags

预定义常量

下列常量由此驱动定义，且仅在扩展编译入 PHP 或在运行时动态载入时可用。另外，使用此驱动时，仅会使用这些驱动特定的常量。使用其他驱动的驱动特定的常量可能会导致不可预见的情况。如果代码可运行于多个驱动，PDO::getAttribute() 可被用于获取 PDO_ATTR_DRIVER_NAME 属性以检查驱动。

PDO::ODBC_ATTR_USE_CURSOR_LIBRARY (int)

This option controls whether the ODBC cursor library is used. The ODBC cursor library supports some advanced ODBC features (e.g. block scrollable cursors), which may not be implemented by the driver. The following values are supported:

  • PDO::ODBC_SQL_USE_IF_NEEDED (the default): use the ODBC cursor library when needed.

  • PDO::ODBC_SQL_USE_DRIVER: never use the ODBC cursor library.

  • PDO::ODBC_SQL_USE_ODBC: always use the ODBC cursor library.

PDO::ODBC_ATTR_ASSUME_UTF8 (bool)

Windows only. If true, UTF-16 encoded character data (CHAR, VARCHAR and LONGVARCHAR) is converted to UTF-8 when reading from or writing data to the database. If false (the default), character encoding conversion may be done by the driver.

运行时配置

这些函数的行为受 php.ini 中的设置影响。

PDO_ODBC Configuration Options
名字 默认 可修改范围 更新日志
pdo_odbc.connection_pooling "strict" PHP_INI_ALL  
pdo_odbc.db2_instance_name NULL PHP_INI_SYSTEM 本过时特性将肯定会在未来被移除。
有关 PHP_INI_* 样式的更多详情与定义，见 配置可被设定范围。

这是配置指令的简短说明。

pdo_odbc.connection_pooling string

Whether to pool ODBC connections. Can be one of "strict", "relaxed" or "off" (equals to ""). The parameter describes how strict the connection manager should be when matching connection parameters to existing pooled connections. strict is the recommend default, and will result in the use of cached connections only when all the connection parameters match exactly. relaxed will result in the use of cached connections when similar connection parameters are used. This can result in increased use of the cache, at the risk of bleeding connection information between (for example) virtual hosts.

This setting can only be changed from the php.ini file, and affects the entire process; any other modules loaded into the process that use the same ODBC libraries will be affected too, including the Unified ODBC extension.

警告

relaxed matching should not be used on a shared server, for security reasons.

小技巧

Leave this setting at the default strict setting unless you have good reason to change it.

pdo_odbc.db2_instance_name string

If you compile PDO_ODBC using the db2 flavour, this setting sets the value of the DB2INSTANCE environment variable on Linux and UNIX operating systems to the specified name of the DB2 instance. This enables PDO_ODBC to resolve the location of the DB2 libraries and make cataloged connections to DB2 databases.

This setting can only be changed from the php.ini file, and affects the entire process; any other modules loaded into the process that use the same ODBC libraries will be affected too, including the Unified ODBC extension.

This setting has no effect on Windows.

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