在 where 子句中获取 END AS 列的值

Question

我有一个查询，我使用 case when to KNOWN_AS 列说明当它的 null 时然后“null”否则“not null”以 known_as2 结尾。现在在 where 子句中，我想引入仅包含 'Not null' 的行。

SELECT i.individual_ref, 0, 'KNOWNAS', i.FORENAMES, i.KNOWN_AS,
       case when KNOWN_AS is null then 'Null'  else ' Not null' end as known_as
FROM TestDatabase.dbo.INDIVIDUAL I
JOIN TestDatabase.dbo.MEMBER M ON M.INDIVIDUAL_REF=I.INDIVIDUAL_REF
WHERE  m.member_status IN(33,1316) 
  AND i.KNOWN_AS IS null or i.KNOWN_AS=''
  and m.MEMBER_STATUS in (33,1316)
  and LEN(i.FORENAMES) > '1' and i.FORENAMES !=''
  AND i.FORENAMES IS NOT NULL 

我需要帮助的原因是：-

我有一个包含 Forename、surname 和 known_as 字段的表。 我想获取 known_as 字段为空白/空且名字不为空或空白且名字长度为 >1 的成员。我怎样才能实现它。成员状态来自另一个表调用成员，我希望成员处于活动和待处理状态，因此我说 WHERE m.member_status IN (33,1316)。请有任何解决方案。

我终于用

解决了

 SELECT i.individual_ref,0,'KNOWNAS',
case when KNOWN_AS is null then 'Null'  else ' Not null' end as knownas2
FROM TestDatabase.dbo.INDIVIDUAL I
JOIN TestDatabase.dbo.MEMBER M ON M.INDIVIDUAL_REF=I.INDIVIDUAL_REF
       WHERE  m.member_status IN(33,1316) 
       and len(i.forenames)>2 and
          (IsNull(i.forenames, '') <> '') and (i.known_as is null or i.known_as='')

我不得不取 len(i.forenames, '')>2 而不是 1，因为有些成员的名字也被错误地更新为 Mr.

Answer 1

现在在 where 子句中，我想引入仅包含 'Not null' 的行。

只需将 WHERE 子句修改为 IS NOT NULL 为：

SELECT i.individual_ref, 0, 'KNOWNAS', i.FORENAMES, i.KNOWN_AS
FROM DiTestDatabase.dbo.INDIVIDUAL I JOIN 
     DiTestDatabase.dbo.MEMBER M 
     ON M.INDIVIDUAL_REF = I.INDIVIDUAL_REF
WHERE m.member_status IN (33,1316) AND
      LEN(i.FORENAMES) > 1 AND i.FORENAMES != '' AND 
      i.FORENAMES IS NOT NULL AND i.KNOWN_AS IS NOT NULL;

注意：

• LEN() 将返回 INT 类型。所以，你不需要使用''。

Answer 2

下面的查询可能会对你有所帮助。

SELECT i.individual_ref, 0, 'KNOWNAS', i.FORENAMES, i.KNOWN_AS
,CASE WHEN i.KNOWN_AS IS NULL THEN 'null'
      ELSE 'Not null' END AS KNOWN_AS2
FROM DiTestDatabase.dbo.INDIVIDUAL I JOIN 
     DiTestDatabase.dbo.MEMBER M 
     ON M.INDIVIDUAL_REF = I.INDIVIDUAL_REF
WHERE m.member_status IN (33,1316) AND
      LEN(i.FORENAMES) > 1 AND i.FORENAMES != '' AND 
      i.FORENAMES IS NOT NULL AND i.KNOWN_AS IS NOT NULL;

Answer 3

这样我们可以得到解决方案

SELECT * FROM ( SELECT i.individual_ref, 0, 'KNOWNAS', i.FORENAMES, i.KNOWN_AS, case when KNOWN_AS is null then 'Null' else 'Not null' end as known_as FROM DiTestDatabase.dbo.INDIVIDUAL I JOIN DiTestDatabase.dbo.MEMBER M ON M.INDIVIDUAL_REF=I.INDIVIDUAL_REF WHERE m.member_status IN(33,1316) AND i.KNOWN_AS IS null or i.KNOWN_AS='' and m.MEMBER_STATUS in (33,1316) and LEN(i.FORENAMES) > 1 and i.FORENAMES !='' AND i.FORENAMES IS NOT NULL) t WHERE t.known_as='Not null'