WHERE CASE 返回多行

Question

我希望此查询 return 只有一行。我已经按照它们最有可能出现的顺序放置了 CASE 语句的 WHEN 子句，所以最有可能的 TRUE 语句将始终首先被评估。但是，似乎每个 WHEN 语句都在查询完成之前被评估，尽管它找到了多个 TRUE 语句。

SELECT To_Char(T.PRFINISH, 'DD/MM/YY') FINISH,
       T.PRNAME  
FROM  PRTASK T
      LEFT OUTER JOIN INV_INVESTMENTS ON T.PRPROJECTID = INV_INVESTMENTS.ID
WHERE T.PRNAME = CASE 
                    WHEN (T.PRNAME = 'Concept Tech PEP Meeting Date' AND T.PRSTATUS != 2) THEN 'Concept Tech PEP Meeting Date'
                    WHEN (T.PRNAME = 'Concept BRU Meeting Date' AND T.PRSTATUS != 2) THEN 'Concept BRU Meeting Date'
                    WHEN (T.PRNAME = 'End of Concept Phase' AND T.PRSTATUS != 2) THEN 'End of Concept Phase'                                                                                                                 
                    WHEN (T.PRNAME = 'Evaluate Tech PEP Meeting Date' AND T.PRSTATUS != 2) THEN 'Evaluate Tech PEP Meeting Date'
                    WHEN (T.PRNAME = 'Evaluate BRU Meeting Date' AND T.PRSTATUS != 2) THEN 'Evaluate BRU Meeting Date'
                    WHEN (T.PRNAME = 'Evaluate TSC Meeting Date' AND T.PRSTATUS != 2) THEN 'Evaluate TSC Meeting Date'
                    WHEN (T.PRNAME = 'End of Evaluate Phase' AND T.PRSTATUS != 2) THEN 'End of Evaluate Phase'                       
                    WHEN (T.PRNAME = 'End of Analyse Phase' AND T.PRSTATUS != 2) THEN 'End of Analyse Phase'
                    WHEN (T.PRNAME = 'End of Design Phase' AND T.PRSTATUS != 2) THEN 'End of Design Phase'
                    WHEN (T.PRNAME = 'End of Build Phase' AND T.PRSTATUS != 2) THEN 'End of Build Phase'
                    WHEN (T.PRNAME = 'End of Test Phase' AND T.PRSTATUS != 2) THEN 'End of Test Phase'
                    WHEN (T.PRNAME = 'In Service' AND T.PRSTATUS != 2) THEN 'In Service'                    
                    WHEN (T.PRNAME = 'End of Implement Phase' AND T.PRSTATUS != 2) THEN 'End of Implement Phase'  
                    WHEN (T.PRNAME = 'End of Closure Phase' AND T.PRSTATUS != 2) THEN 'End of Closure Phase'
                    ELSE 'In Service'
               END
          AND INV_INVESTMENTS.CODE = '007058'

这 return 不止一行，即使第一个 WHEN 子句为真。我认为 CASE 语句在找到 TRUE 语句时就结束了。

编辑：也许我没有很好地解释这一点，让我们试试这个：

在INV_INVESTMENTStable中的每个ID都是一个项目。每个项目在 PRTASK table 中都有一组任务。在这个 PRTASK table 中，我们将有任务名称 (PRNAME)、状态 (PRSTATUS) 和完成日期 (PRFINISH)。任务列表，按照它们在项目中出现的顺序是：

1.概念技术 PEP 会议日期
2。概念 BRU 会议日期
3。概念阶段结束
4。评估技术 PEP 会议日期
5。评估 BRU 会议日期
6.评估 TSC 会议日期

其余任务按照我在 CASE 语句中列出的顺序进行。我希望此查询 return 是列表中 PRSTATUS 为 0 或 1 的第一个任务的完成日期。

Answer 1

试试这个。您可以将已知名称放入 table，然后在联接中使用它。这会将您的 select 简化为以下内容：

SELECT TOP 1 To_Char(T.PRFINISH, 'DD/MM/YY') FINISH,
       T.PRNAME  
FROM  PRTASK T
      LEFT OUTER JOIN INV_INVESTMENTS ON T.PRPROJECTID = INV_INVESTMENTS.ID
      JOIN ( 
      SELECT 'Concept Tech PEP Meeting Date' as Name, 1 as [Order]
      UNION All
      SELECT '<your next PRNAME here', 2 as [Order]
      UNION ALL ...
      ) names on names.Name = T.PRNAME
where PRSTATUS IN (0,1) AND PRINV_INVESTMENTS.CODE = '007058'
ORDER BY names.Order

Answer 2

我还是不明白你想做什么（没有给出示例 data/results），但我会像这样重组它：

SELECT To_Char(PRFINISH, 'DD/MM/YY') AS FINISH, PRNAME
FROM ( 
  SELECT MAX(PRFINISH),
         PRNAME  
  FROM  PRTASK AS T
  WHERE  (PRNAME = 'In Service' OR PRSTATUS != 2)
  AND    PRPROJECTID IN 
    (SELECT ID 
     FROM INV_INVESTMENTS
     WHERE CODE = '007058' )
  GROUP BY PRNAME
  ) AS TABLE1

请注意，这是假设您在查询中列出了 PRNAME 的所有可能值。

WHERE CASE 返回多行

WHERE CASE returning multiple rows

sql

case