PHP PDO的setAttribute函数

数据库的连接：

$dsn = 'mysql:host=127.0.0.1;port=3306;dbname=cardslg';
$username = 'root';
$password = '';
$options = array(
    PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8',
);
$pdo = new PDO($dsn,$username,$password,$options);

$stmt = $pdo->prepare("SELECT * FROM card_users");

1.PDO::ATTR_CASE ：强制列名为指定的大小写。

 1)PDO::CASE_UPPER ：强制列名大写。

$pdo->setAttribute(PDO::ATTR_CASE,PDO::CASE_UPPER);
$stmt = $pdo->prepare("SELECT * FROM card_users");
$stmt->setFetchMode(PDO::FETCH_OBJ);
$stmt->execute();
$queries = $stmt->fetch();

file_put_contents("log.txt",print_r($queries,true));

结果：

stdClass Object
(
    [ID] => 1
    [USER_NAME] => lvpeilin
    [VIP] => 10
    [CONSORTIUM_ID] => 1
    [CREATED_AT] => 2016-12-16 11:55:30
)

2)PDO::CASE_LOWER ：强制列名小写。

$pdo->setAttribute(PDO::ATTR_CASE,PDO::CASE_LOWER);
$stmt = $pdo->prepare("SELECT * FROM card_users");
$stmt->setFetchMode(PDO::FETCH_OBJ);
$stmt->execute();
$queries = $stmt->fetch();

file_put_contents("log.txt",print_r($queries,true));

结果：

stdClass Object
(
    [id] => 1
    [user_name] => lvpeilin
    [vip] => 10
    [consortium_id] => 1
    [created_at] => 2016-12-16 11:55:30
)

3）PDO::CASE_NATURAL ：保留数据库驱动返回的列名。

$pdo->setAttribute(PDO::ATTR_CASE,PDO::CASE_LOWER);
$stmt = $pdo->prepare("SELECT * FROM card_users");
$stmt->setFetchMode(PDO::FETCH_OBJ);
$stmt->execute();
$queries = $stmt->fetch();

结果：

stdClass Object
(
    [id] => 1
    [user_name] => lvpeilin
    [vip] => 10
    [consortium_id] => 1
    [created_at] => 2016-12-16 11:55:30
)