Question

如果NOT IN EXISTS与NOT IN正常工作，我怎么能在这里工作？我应该使用NOT EXISTS得到相同的结果，但我不是。

我使用NOT EXISTS句子的逻辑有什么问题

NOT EXISTS应与A.C_SEQUENCE比较，如NOT IN。与NOT IN相同的逻辑给了我正确的记录。

Select A.C_SEQUENCE, A.STATUS 
FROM PROD.CONTROL A
where A.AID = 'BILLINGS'
and A.USER='GLOBAL_NETWORK'
--and A.STATUS = 'ON'
and NOT EXISTS
(
        select B.H_SEQUENCE
        from PROD.STATUS_R B, PROD.CONTROL A
        where A.USER='GLOBALNETWORK'
        and A.C_SEQUENCE = B.H_SEQUENCE 
        and B.H_STAT in('IGN','ACK')
)
order by C_date DESC limit 5000

Select A.C_SEQUENCE, A.STATUS 
FROM PROD.CONTROL A
where A.AID = 'BILLINGS'
and A.USER='GLOBAL_NETWORK'
--and A.STATUS = 'ON'
and A.C_SEQUENCE NOT IN 
(
        select B.H_SEQUENCE
        from PROD.STATUS_R B, PROD.CONTROL A
        where A.USER='GLOBALNETWORK'
        and A.C_SEQUENCE = B.H_SEQUENCE 
        and B.H_STAT in('IGN','ACK')
)
order by C_date DESC limit 5000

Answer 1

如果没有样本数据，这只是一个黑暗的镜头，但我会用这样的方式编写NOT EXISTS版本：

Select A.C_SEQUENCE, A.STATUS 
FROM PROD.CONTROL A
where A.AID = 'BILLINGS'
and A.USER='GLOBAL_NETWORK'
--and A.STATUS = 'ON'
and NOT EXISTS
(
        select *
        from PROD.STATUS_R B
        and A.C_SEQUENCE = B.H_SEQUENCE 
        and B.H_STAT in('IGN','ACK')
)
order by C_date DESC limit 5000

NOT EXISTS表示您只需要外部选择记录，其中子选择不返回记录。但实际上，由于子选择不包含很多尚未包含在外部选择中的内容，因此编写此类内容可能会更好：

Select A.C_SEQUENCE, A.STATUS 
FROM PROD.CONTROL A
  left exception join prod.status_r_b b
    on b.h_sequence = a.c_sequence
      and b.h_stat in ('IGN', 'ACK')
where A.AID = 'BILLINGS'
  and A.USER='GLOBAL_NETWORK'
--and A.STATUS = 'ON'
order by C_date DESC limit 5000

您还应该能够简化NOT IN这样的版本：

Select A.C_SEQUENCE, A.STATUS 
FROM PROD.CONTROL A
where A.AID = 'BILLINGS'
and A.USER='GLOBAL_NETWORK'
--and A.STATUS = 'ON'
and A.C_SEQUENCE NOT IN 
(
        select B.H_SEQUENCE
        from PROD.STATUS_R B
        and B.H_STAT in('IGN','ACK')
)
order by C_date DESC limit 5000

在这种情况下，NOT IN确认可以返回行，但您只会从prod.control中选择序列号不在过滤的prod.status_r结果集中的行。< / p>

“NOT EXISTS”只能通过交换句子来代替“NOT IN”吗？

1 个答案: