请问一下php的pdo如何插入一个新字段？谢谢了！

$config = [

'user' =>'root',

'passwd' =>'root',

]

try {

$db = new PDO('mysql:host=172.17.0.1port=3306dbname=test', $config['user'], $config['passwd'])

# 新建一张表 A

$db->exec('create table if not exists A (

id int unsigned not null primary key auto_increment comment \'主键id\'

)')

# 给表 A 新增一个字段 name

$db->exec('alter table A add column name varchar(50) not NULL default \'\' comment \'名称\'')

} catch (PODException $e) {

print("Error: " . $e->getMessage())

exit()

}

<?php

$sql="alter table diy_form add name_1 varchar(50) not null"

//php执行语句

$result=mysql_query($sql)

//判断是否成功

if($result){

echo ("

<script type='text/javascript'>alert('增加成功！')history.back()</script>"

)

exit

}

?>

测试时，请把注释除掉