PHP / SQL，简单选择将“值”作为列

Question

$account = "proot"; 

        $sql_check_account = mysqli_query($connect, "SELECT username FROM proot_accounts WHERE username = $account");

    if(!$sql_check_account)
            die(mysqli_error($connect));

Return :

Unknown column 'proot' in 'where clause'

Same with :

 $sql_check_account = mysqli_query($connect, 'SELECT username FROM proot_accounts WHERE username = "'.$account.'"');

Or

 $sql_check_account = mysqli_query($connect, "SELECT username FROM proot_accounts WHERE username =".$account);

What can make the variable $account perform as a column ? I don't get the problem here...

Thanks !

Answer 1

You need to put quotes around it.

mysqli_query($connect, "SELECT username FROM proot_accounts WHERE username = '$account'");

You should also explore prepared SQL statements in PHP. They will save a lot of these formatting headaches.