MYSQL，PHP，PDO检查行是否存在

Question

我试图查看$ steamId中存储的值是否已经存在于表中，但它无法正常工作。我做错了什么。

Account_info表

+------------+---------+----------+-----+
| Steam_id   | Partner | Token    | RID |
+------------+---------+----------+-----+
| Steamid222 | Part222 | token222 |   1 |
+------------+---------+----------+-----+

$stmt = $conn->prepare("SELECT Steam_id from Account_info WHERE Steam_id = ':id'");
$stmt->bindParam(":id", '$steamId');
$stmt->execute();    

if($stmt->rowCount() > 0)
{
//user exists
}
else
{
//user doesn't exist
}

Answer 1

您将确切的字符串'$steamId'绑定到ID，以便搜索ID为'$steamId'的用户。

$stmt->bindParam(":id", $steamId, PDO::PARAM_STR);

您也可以从select语句中删除引号。

$stmt = $conn->prepare("SELECT Steam_id from Account_info WHERE Steam_id = :id");