如何在MySQL選擇從查詢的第一行到一個程序變量

Question

DECLARE topScorer INT default 0; 

SELECT id INTO topScorer FROM game_player 
WHERE game_player.score = (SELECT max(score) FROM game_player) 

了一個壞榜樣，但一個可以很容易地從幼稚編碼結果......它並不在我的測試工作，如果返回了多個行，我怎樣才能得到第一個返回行到變量？

Answer 1

你只需要一個分數？

SELECT id 
    INTO topScorer 
    FROM game_player 
WHERE game_player.score = ( SELECT max(score) as maxScore 
           FROM game_player 
           ) LIMIT 1 

更新： 入佛門先生是正確的，上面的代碼已經被修正。

Answer 2

使用LIMIT x可確保您僅收到查詢中的x行。

在這種情況下，你只想得到1行：

SELECT id 
    INTO topScorer 
    FROM game_player 
WHERE game_player.score = (SELECT max(score) 
           FROM game_player) 
LIMIT 1 

SQL Fiddle DEMO

作爲工作的替代，你也可以使用這個

SELECT id 
    INTO topScorer 
    FROM game_player 
ORDER BY score DESC 
    LIMIT 1 

SQL Fiddle DEMO

Answer 3

申請限制在子查詢中只獲得1個VA泰倫從子查詢

SELECT id 
    INTO topScorer 
    FROM game_player 
WHERE game_player.score = (SELECT max(score) 
           FROM game_player LIMIT 1); 

或獲得從子查詢下面一個使用多個值：

SELECT id 
    INTO topScorer 
    FROM game_player 
WHERE game_player.score in (SELECT max(score) 
           FROM game_player);