PDO如何在预准备语句中将datetime值设置为NULL？

Question

我尝试使用PDO清除日期时间字段的值时出错。问题是，当prepare语句引用字符串时传递NULL值，然后SQL返回错误

Example:
//Test Values
$_POST['FromDate'] = 'NULL';
$_POST['ToDate'] = '20140905';

//Update statement
$SQLQuery = "UPDATE A
             SET
             FromDate = :FromDate
             ,ToDate = :ToDate
             FROM dbo.TEST AS A 
            WHERE
                        ID = 1 ";

//User Params
$UserParams = array(':FromDate' => $_POST['FromDate']
                   ,':ToDate' => $_POST['ToDate']
                   );

//Run the query
$s = $handler->prepare($SQLQuery);
$s->execute(array($UserParams));

SQL查询然后返回错误＆＃39; NULL＆＃39;是一个字符串，FromDate是DATETIME。它必须是NULL而不是＆＃39; NULL＆＃39;

    UPDATE A
    SET
    FromDate = 'NULL'
    etc...

Answer 1

如果您想手动将其设置为NULL，请不要使用post变量。

只需将其硬编码为PHP null对象（当然不是字符串'NULL'）

$stmt = $handler->prepare($SQLQuery);
$success = $stmt->execute(array(':FromDate' => NULL,
                                ':ToDate' => $_POST['ToDate']
));
if($success) {
   echo 'updated!';
} else {
   echo 'failed';
}