PHP PDO
The PHP Data Objects (PDO) extension defines a lightweight, consistent interface for PHP to access databases.
PDO provides a data access abstraction layer, which means that no matter which database is used, the same functions (methods) can be used to query and obtain data.
PDO is released with PHP5.1 and can also be used in the PECL extension of PHP5.0. It cannot run on previous PHP versions.
PDO installation(Recommended learning: PHP video tutorial)
You can check whether the PDO extension is installed through PHP's phpinfo() function .
Installing PDO on Unix systems
On Unix or Linux you need to add the following extensions:
extension=pdo.so
Windows users
PDO and all major drivers are distributed with PHP as shared extensions. To activate them simply edit the php.ini file and add the following extension:
extension=php_pdo.dll
The following constants are defined by this extension module, so they are only available when The modules of this extension are compiled into PHP or are dynamically loaded at runtime.
Note: PDO uses class constants since PHP 5.1. Previous versions used a global constant of the form PDO_PARAM_BOOL.
PDO::PARAM_BOOL (integer) represents the Boolean data type.
PDO::PARAM_NULL (integer) represents the NULL data type in SQL.
PDO::PARAM_INT (integer) represents the integer type in SQL.
PDO::PARAM_STR (integer) Represents a CHAR, VARCHAR, or other string type in SQL.
PDO::PARAM_LOB (integer) represents the large object data type in SQL.
PDO::PARAM_STMT (integer) represents a recordset type. It is not currently supported by any driver.
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