PHP PDO介绍与应用

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　　PDO扩展为PHP访问数据库定义了一个轻量级的、一致性的接口，它提供了一个数据访问抽象层，这样，无论使用什么数据库，都可以通过一致的函数执行查询和获取数据。PDO随PHP5.1发行，在PHP5.0的PECL扩展中也可以使用。
　　在windows环境下PHP5.1以上版本中：
　　PDO和主要数据库的驱动同PHP一起作为扩展发布，要激活它们只需简单的编辑php.ini文件：　　extension=php_pdo.dll　　然后，选择针对特定数据库的DLL文件使用 dl() 在运行时加载，或者在php.ini文件中 php_pdo.dll 行后启用它们，如：　　extension=php_pdo.dll　　extension=php_pdo_firebird.dll　　extension=php_pdo_informix.dll　　extension=php_pdo_mssql.dll　　extension=php_pdo_mysql.dll　　extension=php_pdo_oci.dll　　extension=php_pdo_oci8.dll　　extension=php_pdo_odbc.dll　　extension=php_pdo_pgsql.dll　　extension=php_pdo_sqlite.dll　　这些DLL文件应当存在于系统的 extension_dir 目录里。　　注意 PDO_INFORMIX 只能作为一个PECL扩展使用。
　　类结构：
PDO{
__construct( string$dsn[, string$username[, string$password[, array$driver_options]]] )
boolbeginTransaction( void)
boolcommit( void)
mixederrorCode( void)
arrayerrorInfo( void)
intexec( string$statement)
mixedgetAttribute( int$attribute)
arraygetAvailableDrivers( void)
arrayinTransaction( void)
stringlastInsertId([ string$name = NULL] )
PDOStatementprepare( string$statement[, array$driver_options = array()] )
PDOStatementquery( string$statement)
stringquote( string$string[, int$parameter_type = PDO::PARAM_STR] )
boolrollBack( void)
boolsetAttribute( int$attribute, mixed$value)

}


结构说明

• PDO::beginTransaction— Initiates a transaction（初始事务）
  
• PDO::commit— Commits a transaction（提交事务）
  
• PDO::__construct— Creates a PDO instance representing a connection to a database（创建一个pdo与数据库的实例链接）
  
• PDO::errorCode— Fetch the SQLSTATE associated with the last operation on the database handle
  
• PDO::errorInfo— Fetch extended error information associated with the last operation on the database handle
  
• PDO::exec— Execute an SQL statement and return the number of affected rows（执行sql并返回影响的sql条数）
  
• PDO::getAttribute— Retrieve a database connection attribute
  
• PDO::getAvailableDrivers— Return an array of available PDO drivers
  
• PDO::inTransaction— Checks if inside a transaction
  
• PDO::lastInsertId— Returns the ID of the last inserted row or sequence value
  
• PDO::prepare— Prepares a statement for execution and returns a statement object
  
• PDO::query— Executes an SQL statement, returning a result set as a PDOStatement object
  
• PDO::quote— Quotes a string for use in a query.
  
• PDO::rollBack— Rolls back a transaction（回滚）
  
• PDO::setAttribute— Set an attribute
  

实例演示
Here is an singleton PDO example:###### config.ini ######db_driver=mysqldb_user=rootdb_password=924892xp[dsn]host=localhostport=3306dbname=localhost[db_options]PDO::MYSQL_ATTR_INIT_COMMAND=set names utf8[db_attributes]ATTR_ERRMODE=ERRMODE_EXCEPTION############class Database {private static $link = null ;private static function getLink ( ) {if ( self :: $link ) {return self :: $link ;}$ini = _BASE_DIR . "config.ini" ;$parse = parse_ini_file ( $ini , true ) ;$driver = $parse [ "db_driver" ] ;$dsn = " ${ driver } :" ;$user = $parse [ "db_user" ] ;$password = $parse [ "db_password" ] ;$options = $parse [ "db_options" ] ;$attributes = $parse [ "db_attributes" ] ;foreach ( $parse [ "dsn" ] as $k => $v ) {$dsn .= " ${ k } = ${ v } ;" ;}self :: $link = new PDO ( $dsn , $user , $password , $options ) ;foreach ( $attributes as $k => $v ) {self :: $link -> setAttribute ( constant ( "PDO:: { $k } " ), constant ( "PDO:: { $v } " ) ) ;}return self :: $link ;}public static function __callStatic ( $name , $args ) {$callback = array ( self :: getLink ( ), $name ) ;return call_user_func_array ( $callback , $args ) ;}} ?>// examples$stmt = Database :: prepare ( "SELECT 'something' ;" ) ;$stmt -> execute ( ) ;var_dump ( $stmt -> fetchAll ( ) ) ;$stmt -> closeCursor ( ) ;?>