Question

我有下表

Type    SubType value
A      1       1
A      2       2
A      3       3
A      4       4
B      1       1
B      2       2
B      3       3
C      1       1
C      2       2
C      3       3
C      4       4

我想按所有行进行分组，除非Type = A，输出应该在

之下

Type    Sum
A1    1
A2    2
A3    3 
A4    4
B     6
C     10

是否可以在一个条件下按几行分组，而在另一个条件下分组？

Answer 1

是的，您必须编写一个创建组定义的表达式：

Select case When Type = 'A' then type + ltrim(str(subtype, 9))
            Else Type End Type, Sum(Value) Sum
From table
Group By case When Type = 'A' then type + ltrim(str(subtype, 9))
            Else Type End

Answer 2

是的，您可以GROUP BY CASE表达;

SELECT CASE WHEN type='A' 
            THEN type+CAST(subtype AS VARCHAR(MAX))
            ELSE type END [Type],
       SUM(value) [Sum]
FROM mytable
GROUP BY CASE WHEN type='A'
              THEN type+CAST(subtype AS VARCHAR(MAX))
              ELSE type END
ORDER BY [Type]

An SQLfiddle to test with

在SQL Server 2012中，您可以在不使用强制转换的情况下使用CONCAT，这会稍微简化查询。

Answer 3

另一种选择。将逻辑分为两种情况：

SELECT Type + CAST(subtype AS VARCHAR(MAX)) AS Type,
       SUM(Value) AS Sum
FROM mytable
WHERE Type = 'A'
GROUP BY Type, Subtype

UNION ALL

SELECT Type,
       SUM(Value)
FROM mytable
WHERE Type <> 'A'
GROUP BY Type

ORDER BY Type ;

在 SQL-Fiddle （thnx到@Joachim Isakkson）进行测试

如何使用多个条件进行分组

3 个答案: