mysql sql语句

[q727455218]

求写sql语句

[二月十六]

用case when 做判断实现

[q727455218]

能写个例子出来么 ？ 谢谢

[二月十六]

用mssql写了一个例子，楼主看一下差不多嘛

--测试数据
if not object_id(N'Tempdb..#T') is null
	drop table #T
Go
Create table #T(id INT ,[quality] int,[grade] nvarchar(21))
Insert #T
select 4,5,N'A'union all
select 5,10,N'B' union all
select 6,101,N'D' 

Go
--测试数据结束
DECLARE @a INT = 88
SELECT DISTINCT
        grade
FROM    ( SELECT    CASE WHEN @a <= a.quality THEN a.grade
                         WHEN @a >= a.quality
                              AND @a <= b.quality THEN b.grade
                         WHEN b.quality IS NULL
                              AND @a >= a.quality THEN a.grade
                         ELSE NULL
                    END AS grade
          FROM      #T a
                    LEFT JOIN #T b ON a.id + 1 = b.id
        ) t
WHERE   grade IS NOT NULL;

[q727455218]

[二月十六]

--测试数据
if not object_id(N'Tempdb..#T') is null
    drop table #T
Go
Create table #T(id INT ,[quality] int,[grade] nvarchar(21))
Insert #T
select 4,5,N'A'union all
select 5,10,N'B' union all
select 6,101,N'D' 
 
Go
--测试数据结束
DECLARE @a INT = 7
SELECT DISTINCT
        grade
FROM    ( SELECT    CASE WHEN @a <= a.quality
                              AND a.id = ( SELECT   MIN(id)
                                           FROM     #T
                                         ) THEN a.grade
                         WHEN @a >= a.quality
                              AND @a <= b.quality THEN b.grade
                         WHEN b.quality IS NULL
                              AND @a >= a.quality THEN a.grade
                         ELSE NULL
                    END AS grade
          FROM      #T a
                    LEFT JOIN #T b ON a.id + 1 = b.id
        ) t
WHERE   grade IS NOT NULL;

[RINK_1]

SELECT TOP 1 * FROM table WHERE QUALITY>a ORDER BY QUALITY

[RINK_1]

mysql的是这个 SELECT * FROM #T WHERE QUALITY>a ORDER BY QUALITY limit 0,1

[q727455218]

MIN(id) 不能根据ID来

[q727455218]

有QQ 没加个 可以详细聊下