2. 字段最大值(10分)
有三个字段,col1, col2, col3,如下图所示,请问怎么返回一个字段,值是这三个字段的最大值?
Table1
ID col1 col2 col3
1 10 11 12
2 21 22 20
3 32 30 31
要求得到结果:
ID MaxCol
1 12
2 22
3 32
SQL SERVER 2000
有三个字段,col1, col2, col3,如下图所示,请问怎么返回一个字段,值是这三个字段的最大值?
Table1
ID col1 col2 col3
1 10 11 12
2 21 22 20
3 32 30 31
要求得到结果:
ID MaxCol
1 12
2 22
3 32
SQL SERVER 2000
SELECT [ID] , col1 FROM Table1
UNION ALL
SELECT [ID] , col2 FROM Table1
UNION ALL
SELECT [ID] , col3 FROM Table1
) A GROUP BY [ID]
SELECT [ID] , col1 FROM Table1
UNION ALL
SELECT [ID] , col2 FROM Table1
UNION ALL
SELECT [ID] , col3 FROM Table1
) A GROUP BY [ID]内联!!!~~
SELECT [ID] , col1 FROM Table1
UNION ALL
SELECT [ID] , col2 FROM Table1
UNION ALL
SELECT [ID] , col3 FROM Table1
) A GROUP BY [ID]
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