Question

感谢您的审核。我迫切需要帮助，甚至在下面的问题上明确表示有困难......

使用SQL 2008我有一个设置了五列的表。

数据实际上看起来像这样：

column1 column2 column3 column4 column5
T1      N1      A1      L1      S1
T1      N2      A2      L2      S4
T1      N2      A3      L2      S2
T1      N2      A1      L2      S4
T2      N6      A3      L3      S2
T2      N7      A3      L3      S4
T2      N7      A3      L4      S4
...

对于具有相同column1值的记录，我想确定column2到column5的每个唯一排列。

我想回答这样的问题：

案例1

存在多少条记录

column1 is the same value and
column2 is the same value and
column3 is the same value and
column4 is the same value and
column5 is different

然后

案例2

column1 is the same value and
column2 is the same value and
column3 is the same value and
column4 is different and
column5 is the same value

然后

案例3

column1 is the same value and
column2 is the same value and
column3 is the same value and
column4 is different and
column5 is different

等等。谢谢！

Answer 1

您可以在一个查询中执行此操作，方法是在查询中设置所需排列的表格以及一些case逻辑。

以下是三列的示例。

with t as (
      select 'a' as a, 'b' as b, 'c' as c union all
      select 'a', 'b', 'd' union all
      select 'e', 'b', 'd'
     ),
     perms as (
      select 1 as col1, 1 as col2, 1 as col3 union all
      select 1, 1, 0 union all
      select 1, 0, 0 union all
      select 0, 1, 1 union all
      select 0, 1, 0 union all
      select 0, 0, 1
     )
select (case when p.col1 = 1 then a end) as col1,
       (case when p.col2 = 1 then b end) as col2,
       (case when p.col3 = 1 then c end) as col3,
       count(*)
from t cross join
     perms p
group by (case when p.col1 = 1 then a end),
         (case when p.col2 = 1 then b end),
         (case when p.col3 = 1 then c end)

Answer 2

嗯。如果您想手动执行此操作，则应使用具有多个键的group by之类的操作。例如。对于案例1，您应该执行以下操作：

select column1,column2,column3, column4, count(column5) group by column1,column2,column3, column4

这应该为column1-column4的每个唯一组合提供唯一记录。如果你想要不同，那么你可能需要做一些预处理。

如果您想要更灵活，可能是执行分组的商店程序可能是一个解决方案。

SQL - 如何识别多个键值的排列

2 个答案: