如何组合 2 个查询？答案

【问题标题】：How can I combine 2 queries?如何组合 2 个查询？
【发布时间】：2016-10-04 20:16:13
【问题描述】：

我在 fastreport 中有以下这些查询。我想将它们组合成一个查询。我该怎么做？

SELECT 
    EAMEMID, COUNT (EAMATTNSTATUS)/2 as ABSENTDAYS1
FROM 
    viewDAILYSUM  
WHERE 
    (EAMEMID = :EAMEMID) 
    AND (EAMDATE BETWEEN :FDate AND :TDate)
    AND (EAMATTNSTATUS IN (7, 8))           
GROUP BY 
    EAMEMID  
ORDER BY 
    EAMEMID

SELECT 
    EAMEMID, COUNT(DISTINCT EAMDATE) ABSENTDAYS        
FROM 
    viewDAILYSUM  
WHERE 
    (EAMEMID = :EAMEMID) 
    AND (EAMDATE BETWEEN :FDate AND :TDate)
    AND (EAMATTNSTATUS IN (6))
GROUP BY 
    EAMEMID
ORDER BY 
    EAMEMID

【问题讨论】：

标签： sql fastreport

【解决方案1】：

您可以使用条件聚合：

SELECT EAMEMID,
       SUM(CASE WHEN EAMATTNSTATUS in (7, 8) THEN 1 ELSE 0 END) / 2 as ABSENTDAYS1,
       COUNT(DISTINCT CASE WHEN EAMATTNSTATUS in (6) THEN EAMDATE
             END) as ABSENTDAYS  
FROM viewDAILYSUM  
WHERE (EAMEMID = :EAMEMID) AND
      (EAMDATE between :FDate and :TDate)
GROUP BY EAMEMID  
ORDER BY EAMEMID

【讨论】：

感谢您的快速回复。真的很感激。但让我稍微改变一下我的问题。我迫切需要通过键入一个查询来总结 2 个查询的输出？我可以这样做吗？
@majed 。 . .如果您需要对这些值求和，只需在select 中的表达式之间使用+。

【解决方案2】：

你可以同样的方式使用union：

SELECT * FROM
(
  SELECT 
    1 AS NUMQUERY, EAMEMID, COUNT(EAMATTNSTATUS)/2 as ABSENTDAYS
  FROM 
    viewDAILYSUM  
  WHERE 
    (EAMEMID = :EAMEMID) 
    AND (EAMDATE BETWEEN :FDate AND :TDate)
    AND (EAMATTNSTATUS IN (7, 8))           
  GROUP BY 
    EAMEMID

  UNION

  SELECT 
    2, EAMEMID, COUNT(DISTINCT EAMDATE)        
  FROM 
    viewDAILYSUM  
  WHERE 
    (EAMEMID = :EAMEMID) 
    AND (EAMDATE BETWEEN :FDate AND :TDate)
    AND (EAMATTNSTATUS IN (6))
  GROUP BY 
    EAMEMID
)
ORDER BY NUMQUERY, EAMEMID

【讨论】：

【解决方案3】：

您可以在动态表上进行连接（左，因为两个选择不是同一个 eamemid）

select 
    t1.EAMEMID, t1.ABSENTDAYS1, t2.ABSENTDAYS 
from
    (SELECT 
         EAMEMID, COUNT (EAMATTNSTATUS)/2 as ABSENTDAYS1
     FROM 
         viewDAILYSUM  
     WHERE 
         (EAMEMID = :EAMEMID) 
         AND (EAMDATE BETWEEN :FDate AND :TDate)
         AND (EAMATTNSTATUS IN (7, 8))           
     GROUP BY
         EAMEMID) t1
left join
    (SELECT 
         EAMEMID, COUNT(DISTINCT EAMDATE) ABSENTDAYS        
     FROM  
         viewDAILYSUM  
     WHERE 
         (EAMEMID = :EAMEMID) 
         AND (EAMDATE BETWEEN :FDate AND :TDate)
         AND (EAMATTNSTATUS IN (6))                                                             
     GROUP BY 
         EAMEMID) t2 on t1.EAMEMID = t2.EAMEMID
order by
    t1.EAMEMID

【讨论】：