PHP MySQL检查ID是否存在

Question

I did something like that but it doesn't work.

I want to check if the ID exisit in the data base if yes INSERT the data if not try again.

I use this code to check but doesn't seems to work.

I enter a correct or not correct it goes to the accepted.html page and it doesn't insert the data in my time sheet. I want it to check if the ID is true insert the data in the time sheet.

 if ($player == null || $witness == null) {
        echo "Do not use the same player and witness or maybe you forgot to add it...";
        echo '<META HTTP-EQUIV="Refresh" Content="2; URL=index.php">';
    } else {
        $sql = "SELECT (`id`) FROM player WHERE id={$player} ";
        $result = mysql_query($sql);
        if ($result == true) {
            $sql2 = "INSERT INTO `members` (`player`, `hours`, `minutes`, `witness`, `type`,`date`,`comments`) VALUES ('$player', '$hours', '$minutes', '$witness', '$type', '$date','$comments')";
            $result2 = mysql_query($sql2);

            if ($result2)
            {
                header('Location: accepted.html');
            }
            else {
                echo mysql_error();
            }
        }else{
            header('Location: contactAdmin.html');
        }
    }

Answer 1

$sql = "SELECT (`id`) FROM $tbl_name WHERE id=$$player ";

should be

$sql = "SELECT `id` FROM $tbl_name WHERE id= $player ";

you had id=$$player

Answer 2

There are a few things wrong in your code.
One thing is the first sql query is using the wrong variable $$player should be $player :

$sql = "SELECT `id` FROM $tbl_name WHERE id= $player ";

Secondly, your insert query is never executed because you pass in the wrong variable. You passed in $sql instead of $sql2 :

$sql2 = "INSERT INTO `members` (`player`, `hours`, `minutes`, `witness`, `type`,`date`,`comments`) VALUES ('$player', '$hours', '$minutes', '$witness', '$type', '$date','$comments')";
$result2 = mysql_query($sql2);

Thirdly, your header is in the wrong place. It should be place after the opening { :

if ($result2) {
    header('Location: accepted.html');
} else {
    echo mysql_error();
}

Answer 3

I found 3 mistakes... 1 in $sql query, 2, header loading, 3, placement header vs mysql_error.

  if ($player == null || $witness == null) {
            echo "Do not use the same player and witness or maybe you forgot to add it...";
            echo '<META HTTP-EQUIV="Refresh" Content="2; URL=index.php">';
        } else {
            $sql = "SELECT (`id`) FROM $tbl_name WHERE id='{$player}' ";
            $result = mysql_query($sql);
            if (mysql_num_rows($result) <= 0) {
                $sql2 = "INSERT INTO `members` (`player`, `hours`, `minutes`, `witness`, `type`,`date`,`comments`) VALUES ('$player', '$hours', '$minutes', '$witness', '$type', '$date','$comments')";
                $result2 = mysql_query($sql2);

                if ($result2)
                {
                     header('Location: accepted.html');
                }
                else {
                    echo mysql_error();
                }
            }else{
                header('Location: contactAdmin.html');
            }
        }

--- EDIT fourth: $result2 should use $sql2 as query.