Question

我有一个包含以下值的SQL表

       |  col1 | col2|   source |  values
       |  1    |  2  |  A       |   null
       |  1    |  2  |  B       |   1.0
       |  1    |  2  |  C       |   null
       |  1    |  4  |  A       |   2.0
       |  1    |  4  |  B       |   2.0
       |  1    |  4  |  C       |   2.0
       |  1    |  5  |  A       |   null
       |  1    |  5  |  B       |   null
       |  1    |  5  |  C       |   null

如何使用带有标记的col1和col2组获得输出：

所有值都匹配组（flag = 1）
所有值均为null（flag = 2）
某些值为null（flag = 3）

输出：

       |  col1 | col2|   flag
       |  1    |  2  |   3
       |  1    |  4  |   1
       |  1    |  5  |   2

Answer 1

根据您更新的问题

~~或<：strong>：~~

SELECT col1, col2, SUM(CASE WHEN SomeConditionHere THEN 1 ELSE 0 END) AS Flag FROM Table1 GROUP BY col1, col2;

SQL Fiddle Demo

这会给你：

| COL1 | COL2 | FLAG | ---------------------- | 1 | 2 | 2 | | 1 | 4 | 0 | | 1 | 5 | 3 |

请注意：我认为该标志是NULL列中有多少VALUES个值，因此我使用"Values" IS NULL代替{{1} }}。

我无法理解如何在您发布的预期结果中计算SomeConditionHere。您必须使用定义标志的谓词而不是flag。

<击>

更新

试试这个：

"Values" IS NULL

Updated SQL Fiddle Demo

这会给你：

WITH Flags AS ( SELECT col1, col2, COUNT(*) ValuesCount, SUM(CASE WHEN "Values" IS NULL THEN 1 ELSE 0 END) AS NULLValues FROM Table1 GROUP BY col1, col2 ) SELECT col1, col2, Flag = CASE WHEN ValuesCount = NULLValues THEN 2 WHEN NULLVALUES = 0 AND ValuesCount = (SELECT COUNT(*) FROM Table1 t2 WHERE t1.col1 = t2.col1 AND t1.col2 = t2.col2) THEN 1 ELSE 3 END FROM Flags t1;

Answer 2

在SQLServer2005 +

中

;WITH cte AS
 (
  SELECT col1, col2, [values],       
         COUNT(CASE WHEN [values] IS NULL THEN 1 END) OVER(PARTITION BY col1, col2) AS cntNULL,
         COUNT(*) OVER(PARTITION BY col1, col2) AS cntCol
  FROM dbo.test5
  )
  SELECT col1, col2, MAX(CASE WHEN cntNULL = 0 THEN 1
                              WHEN cntNULL = cntCol THEN 2
                              ELSE 3 END) AS flag
  FROM cte
  GROUP BY col1, col2

SQLFiddle上的演示

Answer 3

...如果你想要更便携的SQL，那么没有CTE的解决方案：

select col1,
       col2,
        case 
            when DistinctValuesWithoutNulls = 1 and NullCount = 0 then 1 
            when DistinctValuesWithoutNulls = 0 then 2
            when NullCount > 0 then 3
        end flag
from
(
    select  col1, 
            col2, 
            count(distinct [values]) DistinctValuesWithoutNulls, 
            sum(case when [values] is null then 1 else 0 end) NullCount
    from Table1
    group by col1, col2
) tmp

SQL检查取消组合列值是否匹配

3 个答案:

<击>

更新