Question

我需要编写一个可以执行多项操作的状态。

这是第一个选择计数的选项，它可以正常工作。

select PLANNED 
  from (SELECT count(FACT.EVENT) AS PLANNED
          FROM FACT FACT 
         WHERE FACT.PLANNEDOTGFLAG = 1 
           AND FACT.STARTDATETIME >= SYSDATE - 365
        )

我需要编写另一个语句，该语句将显示来自同一个表示例的不同信息。

select count(effected) 
  from fact 
 where startime between 01/01/2013 and 01/02/2013

我想知道我是否可以做这样的事情

 select PLANNED, 
        Count_EFFECTED
 from ( SELECT count(FACT.EVENT) AS PLANNED 
          FROM FACT FACT 
         WHERE FACT.PLANNEDOTGFLAG = 1 
           AND FACT.STARTDATETIME >= SYSDATE - 365

        union all

        select count(FACT.effected) AS Count_EFFECTED 
          from fact fact 
         where fact.startime between 01/01/2013 and 01/02/2013
       )

第三次嵌套查询

SELECT 
     A.PLANNED, 
     B.effec,
     C.XOUND // not working yet.
FROM 
     (SELECT count(FACT.EVENT) AS PLANNED FROM FACT FACT 
      WHERE FACT.PLANNEDOTGFLAG = 1 AND FACT.STARTDATETIME >= SYSDATE - 365)  A,

     (select count(FACT.effected) AS effec from fact fact
      WHERE FACT.STARTDATETIME between 01/01/2013 and 01/02/2013) B
     //how can I add 3rd select which is nested.
     (select round(FACT.ID) AS XOUND
       FROM 
       (SELECT SUM(FACT.CIM)/SUM(FACT.CUST) AS ID
          FROM FACT FACT
          WHERE FACT.STARTDATETIME between 01/01/2013 and 01/02/2013
            AND OTGFLAG = 1 AND PLANNEDOTGFLAG = 0 )) C

Answer 1

由于您从同一个表中获得两个不同的计数，我建议使用案例陈述：

SELECT 
    Planned_Outages = COUNT(CASE WHEN Fact.PlannedOTGFlag = 1 AND Fact.StartDateTime >= Sysdate - 365 THEN Fact.Event END), 
    Effec = COUNT(CASE WHEN FactStartTime between '01/01/2013' and '01/02/2013' THEN Fact.Effected END)
FROM 
    Fact

Answer 2

您可以使用CASE表达式重写SQL语句：

select count(case 
                when plannedotgflag = 1 AND 
                     startdatetime >= SYSDATE - 365
                then 1
             end 
            ) as planned
     , count(case
               when startime between to_date('01/01/2013', 'dd/mm/yyy') and 
                                     to_date('01/02/2013', 'dd/mm/yyy')
               then 1
             end
            ) as effected
  from fact

Answer 3

你的第二个查询会给你一个错误，因为导致FROM子句的表只会返回一列（2行），第一行会有PLANNED_OUTAGES而第二行会有effect计数。

根据您的要求，您可以将查询更改为：

包含第三个查询：

SELECT A.PLANNED_OUTAGES,B.effec, C.ID
  FROM (SELECT count(FACT.EVENT) AS PLANNED 
          FROM FACT FACT 
         WHERE FACT.PLANNEDOTGFLAG = 1 AND FACT.STARTDATETIME >= SYSDATE - 365)  A,
       (select count(FACT.effected) AS effec 
          from fact fact
         WHERE FACT.STARTDATETIME between 01/01/2013 and 01/02/2013) B,
       (SELECT ROUND(SUM(FACT.CIM)/SUM(FACT.CUST)) AS ID
          FROM FACT FACT
         WHERE FACT.STARTDATETIME between 01/01/2013 and 01/02/2013
           AND OTGFLAG = 1 AND PLANNEDOTGFLAG = 0 
         GROUP BY FACT.CIM,FACT.CUST) C

从查询错误中选择多个

3 个答案: