2. PDO 的使用

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
//$sql = 'insert user(username,password,email) values("wjh",md5("wjh"),"188@qq.com")';
//$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);
}

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();
}

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();
}

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();
}