MySQL存儲過程在選擇語句中說未定義別名

Question

我有以下語句，它會產生此錯誤。很明顯，select語句的第一行中的別名「R」沒有聲明，但它在語句的最後。有人有主意嗎？

＃1327 - 未聲明的變量，R

CREATE PROCEDURE `get_series_completion`(IN team1_id INT, IN team2_id INT, IN round_shortname VARCHAR(5)) 
BEGIN 
    DECLARE num_games_total, num_games_played INT; 

    SELECT COUNT(*) INTO num_games_played, R.games_per_series INTO num_games_total 
    FROM (
     SELECT game_id 
     FROM team_games 
     WHERE team_id IN (team1_id, team2_id) 
     GROUP BY game_id 
      HAVING COUNT(*) = 2 
      AND SUM(standing = 0) = 0 
    ) AS S, rounds AS R ON R.round_shortname = round_shortname; 

    SELECT num_games_played/num_games_total; 
END$$ 

Answer 1

你應該選擇所有列前進入條款，您的查詢應該是：

SELECT COUNT(*), R.games_per_series INTO num_games_played, num_games_total 
    FROM (
     SELECT game_id 
     FROM team_games 
     WHERE team_id IN (team1_id, team2_id) 
     GROUP BY game_id 
      HAVING COUNT(*) = 2 
      AND SUM(standing = 0) = 0 
    ) AS S 
    LEFT OUTER JOIN rounds AS R ON R.round_shortname = round_shortname; 

或

SELECT COUNT(*), R.games_per_series INTO num_games_played, num_games_total 
    FROM (
     SELECT game_id 
     FROM team_games 
     WHERE team_id IN (team1_id, team2_id) 
     GROUP BY game_id 
      HAVING COUNT(*) = 2 
      AND SUM(standing = 0) = 0 
    ) AS S, rounds AS R 
    WHERE R.round_shortname(+) = round_shortname; -- implicit left outer join