Question

I realize that I can do this in code, but I was curious if there’s a straight SQL way to select (for instance) 10 results in addition to the one that your query matches…

so, let’s say I had a database of players all of whom had scores and I wanted to show a user the 5 players whose scores are behind theirs and the 5 ahead… so, I select their row but now should I just use an or in the where clause and say something like…

select score as selectedScore from player_scores where playerId = xxxx
or (score > selectedScore - 5 and score < selectedScore + 5)

I realize that this implies all the scores are in exact order, and I’d modify the query to pull the userIds from those scores, so this is just a pseudo example for the sake of the question.

I suspect that would work, but is that the *right way to approach this?

Answer 1

You can use UNION to combine two queries that use ORDER BY and LIMIT to select the next 5 and the previous 5 respectively; by using a self-join in each query, one can find all other players adjacent to the desired player’s score (this assumes that playerId is unique in player_scores however):

(
  SELECT   p1.playerId, p1.score
  FROM     player_scores AS p1 JOIN player_scores AS p2 ON p1.score >= p2.score
  WHERE    p2.playerId = ?
  ORDER BY p1.score ASC
  LIMIT    6
) UNION ALL (
  SELECT   p1.playerId, p1.score
  FROM     player_scores AS p1 JOIN player_scores AS p2 ON p1.score <  p2.score
  WHERE    p2.playerId = ?
  ORDER BY p1.score ASC
  LIMIT    5
)