Question

我有以下方式的数据......

ColumnA ColumnB
7675    22838
7675    24907
7675    NULL

我希望结果如下.....

ColumnA ColumnB
7675    2  (need total count for Not Null value)
7675    0  (need count 0 for NULL value)

Answer 1

SELECT ColumnA, COUNT(ColumnB) ColumnB
FROM YourTable
GROUP BY ColumnA
UNION ALL
SELECT ColumnA, 0
FROM YourTable
WHERE ColumnB IS NULL
GROUP BY ColumnA

Answer 2

您可以引入一个计算列，指明ColumnB是否为空，并将其与ColumnA一起用作分组标准：

SELECT
  t.ColumnA,
  ColumnB = COUNT(t.ColumnB)
FROM
  dbo.YourTable AS t
CROSS APPLY
  (SELECT CASE WHEN t.ColumnB IS NULL THEN 1 ELSE 0 END) AS x (SubGroup)
GROUP BY
  t.ColumnA,
  x.SubGroup
ORDER BY
  t.ColumnA,
  x.SubGroup
;

对于空子组，COUNT(t.ColumnB)表达式始终为NULL，对于相应的非空子组，它将返回非空条目的数量。

Answer 3

select columnA, 
       count(columnB) as non_null_count, 
       sum(columnB is null) as null_count
from your_table
group by ColumnA

Answer 4

如果有很多行而不是用UNION两次选择所有行，你可以轻松地使用计数和总和，这可能会更快。

SELECT columna, columnb, SUM(mycount) 
FROM
(   SELECT *, COUNT(columnb) as mycount 
    FROM test
    GROUP BY columnb
)t
GROUP BY mycount
ORDER BY CASE WHEN mycount = 0 THEN 1 ELSE 2 END DESC;

Fiddle Demo

按条件分组BY

4 个答案: