Question

我正在使用SQL Union语法，我希望得到如下结果：

+---------------+-----+---------+
|trkBusinessUnit| New | Pending |
+---------------+-----+---------+
|      AIIB         2      0    |
| Credit Control    1      3    |
|  Direct Center    1      2    |
| Financial Ins     1      1    |
| Motor Acclaim     1      0    |
+-------------------------------+

来自我的代码：

SELECT trkBusinessUnit, Count(*) as New,0 as Pending
FROM tblDTPTracker
WHERE trkStatus = 'New'
GROUP BY trkBusinessUnit

UNION

SELECT trkBusinessUnit,0 as New,Count(*) as Pending
FROM tblDTPTracker
WHERE trkStatus = 'Pending'
GROUP BY trkBusinessUnit

但是当前的输出是：

+---------------+-----+---------+
|trkBusinessUnit| New | Pending |
+---------------+-----+---------+
|      AIIB         2      0    |
| Credit Control    1      0    |
| Credit Control    0      3    |
|  Direct Center    1      0    |
|  Direct Center    0      2    |
| Financial Ins     1      0    |
| Financial Ins     0      1    |
| Motor Acclaim     1      0    |
+-------------------------------+

我错过了什么或做错了什么？请建议。

Answer 1

如果我理解正确，你不必使用工会。

尝试：

SELECT 
    trkBusinessUnit, 
    COUNT(CASE WHEN trkStatus = 'New' THEN 1 ELSE NULL END) as New, 
    COUNT(CASE WHEN trkStatus = 'Pending' THEN 1 ELSE NULL END) as Pending
FROM tblDTPTracker
GROUP BY trkBusinessUnit

Answer 2

以前的答案中存在（或已经存在）一些语法问题，但两个早期答案的意图都是正确的，您需要使用GROUP BY查询而不使用UNION - 这只是没有做你希望/期待的事情。

UNION或UNION ALL按行进行ROW，绝对不要通过COLUMN进行合并

因此，基于组的查询的MySQL语法可以是以下任何一种：

COUNT（）使用隐式NULL

SELECT 
       trkBusinessUnit
     , COUNT(CASE WHEN trkStatus = 'New'     THEN 1 END) as New 
     , COUNT(CASE WHEN trkStatus = 'Pending' THEN 1 END) as Pending
FROM tblDTPTracker
GROUP BY trkBusinessUnit
;

COUNT（）使用显式NULL

SELECT 
       trkBusinessUnit
     , COUNT(CASE WHEN trkStatus = 'New'     THEN 1 ELSE NULL END) as New 
     , COUNT(CASE WHEN trkStatus = 'Pending' THEN 1 ELSE NULL END) as Pending
FROM tblDTPTracker
GROUP BY trkBusinessUnit
;

SUM（）作为计数的替代方法：

select
       trkBusinessUnit
     , sum(case when trkStatus = 'New'     then 1 else 0 end) as New
     , sum(case when trkStatus = 'Pending' then 1 else 0 end) as Pending
from tblDTPTracker
where trkStatus in ('Pending', 'New')
group by trkBusinessUnit
;

向Marc Gravell＆amp;在这个回答之前的Daniel Gadawski;这个答案是你的衍生物。

See this SQLFiddle demo of these queries

Answer 3

Union垂直追加行（注意UNION也只占用不同的行; UNION ALL占用所有行）。您想要的是full outer join两个子查询，或更复杂的select。我会选择后者！

select tblDTPTracker,
       sum(case trkStatus when 'New' then 1 else 0 end) as New,
       sum(case trkStatus when 'Pending' then 1 else 0 end) as Pending
from tblDTPTracker
where trkStatus in ('Pending', 'New')
group by tblDTPTracker

完全外连接方法类似于：

SELECT ISNULL(x.trkBusinessUnit, y.trkBusinessUnit) as trkBusinessUnit,
       ISNULL(x.New, 0) as New,
       ISNULL(y.Pending, 0) as Pending
FROM (
    SELECT trkBusinessUnit, Count(1) as New
    FROM tblDTPTracker
    WHERE trkStatus = 'New'
    GROUP BY trkBusinessUnit) x
FULL OUTER JOIN (        
    SELECT trkBusinessUnit, Count(1) as Pending
    FROM tblDTPTracker
    WHERE trkStatus = 'Pending'
    GROUP BY trkBusinessUnit) y on y.trkBusinessUnit = x.trkBusinessUnit

在SQL Union语法中组合数据

3 个答案: