Question

select ac1.ACCT_CODE,
       ac1.PERIOD,
       ac1.MONTH,
       ac1.YEAR,
       ac1.PRD_BDGT,
       ac2.ACCT_CODE,
       ac2.PERIOD,
       ac2.MONTH,
       ac2.YEAR,
       ac2.PRD_BDGT
from account ac1, account ac2
where ac1.acct_code='075200'
    and ac1.year=1994
    and ac1.period between 1 and 6
    and ac2.acct_code=ac1.acct_code
    and ac2.year=1995
    and ac2.period =ac1.period  

union 

select ac3.ACCT_CODE,
       ac3.PERIOD,
       ac3.MONTH,
       ac3.YEAR,
       ac3.PRD_BDGT,
       ac4.ACCT_CODE,
       ac4.PERIOD,
       ac4.MONTH,
       ac4.YEAR,
       ac4.PRD_BDGT
from account ac3, account ac4
where ac3.acct_code='075200'
     and ac3.year=1995
     and ac3.period between 7 and 12
     and ac4.acct_code=ac3.acct_code
     and ac4.year=1996
     and ac4.period=ac3.period

Answer 1

使用OR：

select ac1.ACCT_CODE,
ac1.PERIOD,
ac1.MONTH,
ac1.YEAR,
ac1.PRD_BDGT,
ac2.ACCT_CODE,
ac2.PERIOD,
ac2.MONTH,
ac2.YEAR,
ac2.PRD_BDGT
from account ac1, account ac2
where ac1.acct_code='075200'
    and ac2.acct_code=ac1.acct_code
    and ac2.period =ac1.period
and ((ac1.year=1994
    and ac1.period between 1 and 6
    and ac2.year=1995
 ) OR
    (ac1.year=1995
    and ac1.period between 7 and 12
    and ac2.year=1996))

Answer 2

您的查询正在执行两个非常相似的查询中的union，其中唯一的区别是where子句中的某些条件。您可以使用or子句中的where轻松地将它们组合起来。

以下查询还修复了join语法：

select ac1.ACCT_CODE, ac1.PERIOD, ac1.MONTH, ac1.YEAR, ac1.PRD_BDGT, ac2.ACCT_CODE,
       ac2.PERIOD, ac2.MONTH, ac2.YEAR, ac2.PRD_BDGT 
from account ac1 join
     account ac2 
     on ac2.period = ac1.period and
        ac2.acct_code = ac1.acct_code
where ac1.acct_code='075200' and
      ((ac1.year = 1994 and
        ac1.period between 1 and 6
        ac2.year=1995 
       ) or
       (ac1.year=1995 and
        ac1.period between 7 and 12 and
        ac2.year=1996
       )
      );

如果此查询实际解决了您的业务问题，我会感到惊讶。在accounts表上进行自联接是可疑的。通常，聚合是人们需要的，但我不能说出查询的目的。

请告诉我如何将此查询转换为单个查询

2 个答案: