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An introduction to the functional operations of the PDO data access abstraction layer in PHP
An introduction to the functional operations of the PDO data access abstraction layer in PHP
PDO: Data Access Abstraction Layer
has three major characteristics:
1. Can access other databases. All databases can
2. Has transaction functions
3. With prepared statement function (to prevent SQL injection attacks)
The example operation code is as follows:
<?php //1.造PDO对象 $dsn ="mysql:dbname=mydb;host=localhost";//数据库类型:dbname=数据库名称;host=链接的ip或本机 $pdo =new PDO($dsn,"root","root");//$dsn,帐号，密码 //2.写SQL语句 $sql ="select * from info"; $sql ="insert into info values('004','王六','男','n007','1994-02-11')"; //3.执行SQL语句 $stm = $pdo->query($sql); //查询语句用query,返回的是结果 $arr = $pdo->exec($sql);//增删改用exec，返回的是执行的行数 //4.从PDOStatement对象里面读数据 $arr =$stm->fetch(PDO::FETCH_NUM);//默认不选为PDO::FETCH_BOTH fetch为选择一条数据 $arr = $stm->fetchAll(PDO::FETCH_BOTH);//fetchAll为全选 //事务类型:即要不全部都通过，要不全部失败，可以参考淘宝购物，必须同时满足扣款，减去库存和添加订单三项条件，缺一不可 //beginTransation 启动事务 //commit 提交事务 //rollback 回滚:返回到启动事务之前
//1.造PDO对象
$dsn ="mysql:dbname=mydb;host=localhost";
$pdo =new PDO($dsn,"root","root");
//2.将PDO的错误类型设置为异常模式
$pdo->setAttribute(PDO::ATTR_ERRMODE,PDO::ERRMODE_EXCEPTION);
try //尝试运行,包含从开启事务到提交事务
{
//开启事务
$pdo->beginTransaction();
$sql1 = "insert into info values('004','进口','男','n008','1994-05-11')";
$sql2 = "insert into info values('005','审核','男','n009','1994-07-11')";
$sql3 = "insert into info values('006','姐我','男','n0010','1994-08-11')";
$pdo->exec($sql1);
$pdo->exec($sql2);
$pdo->exec($sql3);
//提交事务
$pdo->commit();
}
catch(Exception $e)
{
//回滚操作
$pdo->rollBack();
}
//强类型语言中使用
final
{
//最终执行，无论有没有异常出现，该代码都会执行
}
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