MySQL对符合特定条件的行的max（date）之前的所有计数

Question

I'm trying to get the last recorded loss, then count the number of wins after that to calculate a win streak.

BEGIN
SET @maxDate:=(SELECT MAX(date) from game_scores where     
user_score<opponent_score and user_id=1);

SELECT @maxDate as last_loss, COUNT(*) as streak from game_scores
WHERE  user_score>opponent_score and date>@maxDate and user_id=1;

END

But I keep getting syntax errors at the SET @maxDate line. Am I close?

Answer 1

You can do this in a single shot if you join to the query for the last loss date.

Also note that, if you've already located the user's last loss date, any of their records after that will be wins so your second query doesn't need to check the user score against the opponent score.

SELECT
  last_recorded_loss.maxDate AS last_loss,
  COUNT(*) AS streak
FROM game_scores
INNER JOIN (
  SELECT MAX(date) AS maxDate
  FROM game_scores
  WHERE user_score < opponent_score
    AND user_id = 1
  ) last_recorded_loss
  ON game_scores.date > last_recorded_loss.maxDate AND
     game_scores.user_id = 1