php pdo对象使用详解: 连接数据库与exec方法

Posted 2020-11-02 ghostwu

要使用pdo，首先需要开启pdo扩展，我这里已经开启了mysql的pdo扩展

[email protected]:~$ php -m | grep pdo
pdo_mysql
[email protected]:~$ 

１，连接数据库

mysql> show create database shop \G;
*************************** 1. row ***************************
       Database: shop
Create Database: CREATE DATABASE `shop` /*!40100 DEFAULT CHARACTER SET utf8 */
1 row in set (0.00 sec)

mysql> show create table account \G;
*************************** 1. row ***************************
       Table: account
Create Table: CREATE TABLE `account` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_name` varchar(20) CHARACTER SET latin1 NOT NULL,
  `user_pwd` varchar(40) CHARACTER SET latin1 NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8

try{
        $dsn = ‘mysql:host=localhost;dbname=shop‘;
        $username = ‘root‘;
        $pwd = ‘root‘;
        $pdo = new PDO( $dsn, $username, $pwd );
        var_dump( $pdo );
    }catch( PDOException $e ) {
        echo $e->getMessage();
    }

>上面为参数形式连接数据库

>uri形式连接数据库

dsn.txt

mysql:host=localhost;dbname=shop;

try{
        $dsn = ‘uri:file:///home/ghostwu/php/php2/pdo/dsn.txt‘;
        $username = ‘root‘;
        $pwd = ‘root‘;
        $pdo = new PDO( $dsn, $username, $pwd );
        var_dump( $pdo );
    }catch( PDOException $e ) {
        echo $e->getMessage();
    }

还有一种是php.ini中写dsn连接信息，不太推荐使用

２，exec执行一条sql语句，返回值为受影响的行数，如果没有受影响的行数，返回值为0，该方法对select语句无效

try{
        $dsn = ‘mysql:host=localhost;dbname=shop‘;
        $username = ‘root‘;
        $pwd = ‘root‘;
        $pdo = new PDO( $dsn, $username, $pwd );

        $sql =<<< SQL
        create table if not exists user(
        id int unsigned not null auto_increment,
        username varchar( 20 ) not null unique,
        pwd char( 32 ) not null,
        email varchar( 30 ) not null,
        primary key( id )    
        )engine myisam;
SQL;
        $res = $pdo->exec( $sql );
        var_dump( $res );
    }catch( PDOException $e ) {
        echo $e->getMessage();
    }

３，执行insert语句

$insertUserSql = "insert into user( username, pwd, email ) values( ‘ghostwu‘," . "‘" . md5( ‘ghostwu‘ )  . "‘" . ",‘[email protected]‘)";
        $res = $pdo->exec( $insertUserSql );
        var_dump( $res );

４，一次性执行多条sql语句

 1 try{
 2         $dsn = ‘mysql:host=localhost;dbname=shop‘;
 3         $username = ‘root‘;
 4         $pwd = ‘root‘;
 5         $pdo = new PDO( $dsn, $username, $pwd );
 6         $bajie = md5( ‘bajie‘ );
 7         $wukong = md5( ‘wukong‘ );
 8         $tangsheng = md5( ‘tangsheng‘ );
 9         $insertUserSql =<<<EOF
10         insert into user( username, pwd, email ) values( ‘wukong‘, ‘$wukong‘, ‘[email protected]‘ ),( ‘bajie‘, ‘$bajie‘,‘[email protected]‘ ),( ‘tangsheng‘, ‘$tangsheng‘,‘[email protected]‘ );
11 EOF;
12         $res = $pdo->exec( $insertUserSql );
13         var_dump( $res );
14     }catch( PDOException $e ) {
15         echo $e->getMessage();
16     }

５，获取最后一次插入数据的自增id

    try{
        $dsn = ‘mysql:host=localhost;dbname=shop‘;
        $username = ‘root‘;
        $pwd = ‘root‘;
        $pdo = new PDO( $dsn, $username, $pwd );
        $insertUserSql = "insert into user( username, pwd, email ) values( ‘zhanzhao‘," . "‘" . md5(‘zhanzhao‘ ) . "‘,‘[email protected]‘)";
        echo $insertUserSql . PHP_EOL;
        $res = $pdo->exec( $insertUserSql );
        echo $pdo->lastInsertId() . PHP_EOL;
    }catch( PDOException $e ) {
        echo $e->getMessage();
    }

６，执行delete语句

try{
        $pdo = new PDO( "mysql:host=localhost;dbname=shop", ‘root‘, ‘root‘ );
        $sql = "delete from user where id = 1";
        $res = $pdo->exec( $sql );
        var_dump( $res );
    }catch( PDOException $e ) {
        echo $e->getMessage();
    }