Question

I have table:

user_id | song_id| points
--------|----------------
  2     |  1     |  0
  2     |  2     |  1
  2     |  3     |  2
  2     |  4     |  3
  2     |  5     |  4

And I need to check if the user have changed the points value.
Therefore it should be something like:

while ($row = mysql_fetch_array($query)) {
    $userID = $row['user_id'];
    $songID = $row['song_id'];
    $points = $row['points'];
if($songID-$points==1){
 echo $userID."<br>";

}

But this will print out every occasion of userID where the song-id – points=1.

I need to print out only these user_id’s that have all the values =1 and the username must echo’d only once.

EDIT:

SELECT DISTINCT user_id WHERE (song_id - points) = 1

This is half way there. This echo’s user_ids’ where the song_id – points = 1, but if the user is reordered (i use jQuery sortable) the list, then there can be some rows that is “song_id – points = 1”.

My script must echo only these user_id-s, where users every song_id – points = 1, not only one

Answer 1

You can first filter the users which has modified point values:

SELECT DISTINCT user_id FROM table
WHERE (song_id - points) != 1

Then you can use fetch the users which doesn’t fit the above condition:

SELECT DISTINCT user_id FROM table
WHERE user_id NOT IN (
  SELECT DISTINCT user_id FROM table
  WHERE (song_id - points) != 1
)

According to your last edit this last SQL statement might work.

You can check a working example.