2. PDO 的使用

1. exec()

1.1 建表
<?php

try {
    $dsn = 'mysql:host=localhost;dbname=test';
    $username = 'root';
    $password = '123456';
    $pdo = new PDO($dsn,$username,$password);

    //exec();执行一条 sql 语句，并返回受影响的记录的条数,如果没有受影响返回0
    //exec 对 select 没有作用
    $sql = <<<EOF
create table if not exists user(
    id int unsigned auto_increment key,
    username varchar(20) not null unique,
    password char(32) not null,
    email varchar(32) not null
)
EOF;

    $res = $pdo->exec($sql);
    var_dump($res);

} catch (PDOException $e) {
    echo $e->getMessage();
}

返回 0；

插入记录：
//插入一条记录
    //$sql = 'insert user(username,password,email) values("wjh",md5("wjh"),"[email protected]")';
    //$res = $pdo->exec($sql);  返回 1

    //插入多条记录
$sql = <<<EOF
    insert user(username,password,email) values("wjh1",md5("wjh"),"188@qq.com"),
    ("wjh2",md5("wjh"),"188@qq.com"),
    ("wjh3",md5("wjh"),"188@qq.com")
EOF;
    $res = $pdo->exec($sql);  // 返回 3
    $pdo->lastInsertId();  //返回 最后一条插入记录的 ID

更新记录：
    $sql = 'update user set username="immoc" where id=3';
    $res = $pdo->exec($sql);

删除记录
    $sql = 'delete from user where id=2';
    $res = $pdo->exec($sql);

获取错误信息：

//删除记录
    $sql = 'delete from user12 where id=2';
    $res = $pdo->exec($sql);
    if ($res === false) {
        //返回数据库句柄上一次操作相关的SQLSTATE的值
        echo $pdo->errorCode();
        echo '<br/>';
        //返回数据库句柄上一次操作错误信息的数组，数组包括3个单元
        //1. 0 => SQLSTATE
        //2. 1 => 错误编号,CODE
        //3. 3 => 信息
        $errInfo = $pdo->errorInfo();
        var_dump($errInfo);
    } else {
        var_dump($res);
    }

2. query()

try {
    $pdo = new PDO('mysql:host=localhost;dbname=test','root','123456');
    //$sql = 'select * from user where id=2;';
    $sql = 'select * from user;';

    //执行 sql 语句，返回PDOStatement对象
    $stmt = $pdo->query($sql);
    foreach ($stmt as $row) {
        echo $row['id'];
        echo '<br/>';
        echo $row['username'];
        echo '<br/>';
        echo $row['password'];
        echo '<br/>';
        echo $row['email'];
        echo '<br/>';
    }

} catch (PDOException $e) {
    echo $e->getMessage();
}

3.prepare() and execute()

try {
    $pdo = new PDO('mysql:host=localhost;dbname=test','root','123456');
    $sql = "select * from user";

    //返回一个 PDOStatement 对象
    //prepare($sql);准备 sql 语句
    $stmt = $pdo->prepare($sql);

    //设置默认的返回模式
    $stmt->setFetchMode(PDO::FETCH_OBJ);

    // execute(); 执行预处理语句,返回布尔值
    $res = $stmt->execute();
    //取出结果集取出一条记录
// $row = $stmt->fetch();
    if ($res) {
        while($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
            var_dump($row );
        }
    }

    //用 fetchAll()
    /*$rows = $stmt->fetchAll(); var_dump($rows);*/




} catch (PDOException $e) {
    echo $e->getMessage();
}

4.getAttribute() and setAttribute()

try {
    $dsn = 'mysql:host=localhost;dbname=test';
    $username = 'root';
    $password = '123456';
    $pdo = new PDO($dsn,$username,$password);
    // 默认为 1 ，自动提交
    echo '自动提交 : ' . $pdo->getAttribute(PDO::ATTR_AUTOCOMMIT);
    echo '<br/>';
    echo '默认错误处理模式 ：' . $pdo->getAttribute(PDO::ATTR_ERRMODE);
    echo '<br/>';
    $pdo->setAttribute(PDO::ATTR_AUTOCOMMIT,0);
    echo '自动提交 : ' . $pdo->getAttribute(PDO::ATTR_AUTOCOMMIT);
} catch (PDOException $e) {
    echo $e->getMessage();
}

<?php try { $dsn = 'mysql:host=localhost;dbname=test'; $username = 'root'; $password = '123456'; $pdo = new PDO($dsn,$username,$password); $attArr = array( 'AUTOCOMMIT', 'CASE', 'CLIENT_VERSION', 'CONNECTION_STATUS', 'DRIVER_NAME', 'ERRMODE', 'ORACLE_NULLS', 'PERSISTENT', 'PREFETCH', 'SERVER_INFO', 'SERVER_VERSION', 'TIMEOUT' ); foreach ($attArr as $attr) { echo "PDO_ATTR_$attr : "; echo $pdo->getAttribute(constant("PDO::ATTR_$attr")); echo '<br/>'; } } catch (PDOException $e) { echo $e->getMessage(); }