WHERE 子句中的条件 (Oracle)

Question

我需要一个根据月份/年份返回数据的查询。下面是我编写的一个子查询，它返回一行 - start_date 和 end_date 是我需要在我的主查询中使用的值

WITH SUBQ AS (SELECT 
    dim.MONTH_NAME as current_month_name
   ,dim.year_period as current_month
   ,dim.PERIOD_YEAR as YEAR
   ,CASE WHEN dim.year_period NOT LIKE '%01' THEN to_number(CONCAT(to_char(dim.PERIOD_YEAR-1) , '01' ))
         WHEN dim.year_period LIKE '%01'THEN to_number(CONCAT(to_char(dim.PERIOD_YEAR-2) , '01' ))
         END AS START_DATE 
   ,CASE WHEN dim.year_period NOT LIKE '%01' THEN to_number(CONCAT(to_char(dim.PERIOD_YEAR) , '01'  ))
         WHEN dim.year_period LIKE '%01'THEN to_number(CONCAT(to_char(dim.PERIOD_YEAR-1) , '01'   )) END AS ENDDATE 
  from dim_periods dim    WHERE dim.year_period=to_number(to_char(sysdate, 'YYYYMM')))

问题是 - 如何在 where 子句中使用子查询中的值和一行？ 我需要得到这样的东西，我只是不明白我应该如何加入我的子查询和我使用的其他表 -

select * from financial_data fd 
where fd.year_period BETWEEN subq.start_date and subq.enddate

Answer 1

您可以将子查询，即CTE与表连接起来，然后在过滤谓词中使用列名。 WITH 子句 中子查询的结果就像一个临时表。

例如，

WITH SUBQ AS
  (SELECT dim.MONTH_NAME AS current_month_name ,
    dim.year_period      AS current_month ,
    dim.PERIOD_YEAR      AS YEAR ,
    CASE
      WHEN dim.year_period NOT LIKE '%01'
      THEN to_number(CONCAT(TO_CHAR(dim.PERIOD_YEAR-1) , '01' ))
      WHEN dim.year_period LIKE '%01'
      THEN to_number(CONCAT(TO_CHAR(dim.PERIOD_YEAR-2) , '01' ))
    END AS START_DATE ,
    CASE
      WHEN dim.year_period NOT LIKE '%01'
      THEN to_number(CONCAT(TO_CHAR(dim.PERIOD_YEAR) , '01' ))
      WHEN dim.year_period LIKE '%01'
      THEN to_number(CONCAT(TO_CHAR(dim.PERIOD_YEAR-1) , '01' ))
    END AS ENDDATE
  FROM dim_periods dim
  WHERE dim.year_period=to_number(TO_CHAR(SYSDATE, 'YYYYMM'))
  )
SELECT fd.COLUMNS,
  q.COLUMNS
FROM financial_data fd
JOIN subq q
ON (fd.KEY = q.KEY) -- join key
WHERE fd.year_period BETWEEN q.start_date AND q.enddate;

因此，SUBQ 就像一个临时表，您可以将其与financial_data 表连接。

UPDATE OP 不需要 ANSI 连接语法。

WITH SUBQ AS
  (SELECT dim.MONTH_NAME AS current_month_name ,
    dim.year_period      AS current_month ,
    dim.PERIOD_YEAR      AS YEAR ,
    CASE
      WHEN dim.year_period NOT LIKE '%01'
      THEN to_number(CONCAT(TO_CHAR(dim.PERIOD_YEAR-1) , '01' ))
      WHEN dim.year_period LIKE '%01'
      THEN to_number(CONCAT(TO_CHAR(dim.PERIOD_YEAR-2) , '01' ))
    END AS START_DATE ,
    CASE
      WHEN dim.year_period NOT LIKE '%01'
      THEN to_number(CONCAT(TO_CHAR(dim.PERIOD_YEAR) , '01' ))
      WHEN dim.year_period LIKE '%01'
      THEN to_number(CONCAT(TO_CHAR(dim.PERIOD_YEAR-1) , '01' ))
    END AS ENDDATE
  FROM dim_periods dim
  WHERE dim.year_period=to_number(TO_CHAR(SYSDATE, 'YYYYMM'))
  )
SELECT fd.COLUMNS,
  q.COLUMNS
FROM financial_data fd,
  subq q
WHERE fd.KEY = q.KEY -- join key
AND fd.year_period BETWEEN q.start_date AND q.enddate;