使用 CASE 一个表达式来告诉你的句子中要省略哪个分数 GREATEST() 打电话。

SELECT id,
    CASE GREATEST(score1, score2, score3, score4)
        WHEN score1 THEN GREATEST(score2, score3, score4)
        WHEN score2 THEN GREATEST(score1, score3, score4)
        WHEN score3 THEN GREATEST(score1, score2, score4)
        ELSE GREATEST(score1, score2, score3)
    END AS col_value
FROM your_table ;

这个解决方案很容易推广到任意数量的列。
和一个没有 CASE ，同时使用 GREATEST() 以及 LEAST() :

SELECT id,
    LEAST(
        GREATEST(score1, score2, score3),
        GREATEST(score2, score3, score4),
        GREATEST(score3, score4, score1),
        GREATEST(score4, score1, score2)
    ) AS col_value
FROM your_table ;

假设没有领带，你可以用一个大的 case 表达式：

select t.*,
       (case when score1 > score2 and score1 > score3 and score1 < score 4 then score1
             when score1 > score2 and score1 < score3 and score1 > score 4 then score1
             when score1 < score2 and score1 > score3 and score1 > score 4 then score1
             when score2 > score1 and score2 > score3 and score2 < score 4 then score2
             when score2 > score1 and score2 < score3 and score2 > score 4 then score2
             when score2 < score1 and score2 > score3 and score2 > score 4 then score2
             . . .
        end) as second_score          
from t;

不过，一般来说，这类问题表明数据结构存在问题。我想你真的应该有一张每张一行的table id 以及 score （也许还有 score 编号）。这在sql中通常更容易操作。

考虑以下更容易概括的问题：

DROP TABLE IF EXISTS my_table;

CREATE TABLE my_table 
(id INT NOT NULL
,score_no INT NOT NULL
,score INT NOT NULL
,PRIMARY KEY(id,score_no)
);

INSERT INTO my_table VALUES
(1, 1 ,10),
(1 ,2 ,05),
(1 ,3 ,30),
(1 ,4 ,50),
(2 ,1 ,05),
(2 ,2 ,15),
(2 ,3 ,10),
(2 ,4 ,00),
(3 ,1 ,25),
(3 ,2 ,10),
(3 ,3 ,05),
(3 ,4 ,15);

SELECT id
     , score_no
     , score 
  FROM 
     ( SELECT x.*
            , CASE WHEN @prev=id THEN @i:=@i+1 ELSE @i:=1 END rank
            , @prev:=id 
         FROM my_table x
            , (SELECT @prev:=null,@i:=0) vars 
        ORDER 
           BY id
            , score DESC
            , score_no 
     ) a
 WHERE rank = 2;
 +----+----------+-------+
 | id | score_no | score |
 +----+----------+-------+
 |  1 |        3 |    30 |
 |  2 |        3 |    10 |
 |  3 |        4 |    15 |
 +----+----------+-------+

如果分数相等，此解决方案将选择“分数不”较低的一个。

使用 UNPIVOT 尝试此查询

CREATE TABLE #my_table
(id INT NOT NULL, score1 INT NOT NULL, score2 INT NOT NULL, score3 INT NOT NULL, score4 INT NOT NULL) 

INSERT INTO #my_table VALUES(1,  10,     05,      30,    50)
INSERT INTO #my_table VALUES(2,  05,     15,      10,    00)
INSERT INTO #my_table VALUES(3,  25,     10,      05,    15)

;WITH getHighestValue as (
SELECT id, Scores, ScoreText, ROW_NUMBER() OVER(PARTITION BY id ORDER BY Scores DESC) AS Ranks
FROM #my_table
UNPIVOT(
Scores for ScoreText in (score1,score2,score3,score4)
) unpiv
)
SELECT id, Scores as col_value 
FROM getHighestValue
WHERE Ranks = 2

结果：