Question

我正在尝试写一个写，而我正在寻找的逻辑基本上就是这样。如果表1中不存在表1中的任何用户ID，则显示结果中的用户ID。所以我做了：

SELECT
  UserColder.ContactName,
  UserColder.Phone,
  UserColder.Email,
  UserColder.Website,
  Country.Name,
  UserColderZIP.[ZIP Code],
  UserColderZIP.[State Abbreviation]
FROM
  dbo.UserColder
  LEFT OUTER JOIN dbo.CountryUser
    ON UserColder.ID = CountryUser.[User ID]
  INNER JOIN dbo.Country
    ON CountryUser.[Foreign ID] = Country.ID
  LEFT OUTER JOIN dbo.UserColderZIP
    ON UserColder.ID = UserColderZIP.UserColder
WHERE
  UserColder.ID NOT IN (CountryUser.[User ID])

它返回没有Where的数据但是使用Where我试图让它显示所有结果，其中来自UserColder的Id在CountryUser中没有任何记录。现在它没有返回任何结果，我知道那里不存在ID 2。知道我做错了吗？

谢谢！

Answer 1

由于您拥有LEFT OUTER JOIN，要从UserColder获取CountryUser中不存在的记录，请检查NULL。没有相应值的连接行将返回NULL。

WHERE
  CountryUser.[User ID] IS NULL

Answer 2

只需从UserColder获取信息，并确保UserColder.ID不在CountryUser中，方法是检查它（select语句在哪里）。

SELECT
  UserColder.ContactName,
  UserColder.Phone,
  UserColder.Email,
  UserColder.Website,
  Country.Name,
  UserColderZIP.[ZIP Code],
  UserColderZIP.[State Abbreviation]
FROM
  dbo.UserColder
  INNER JOIN dbo.Country
    ON CountryUser.[Foreign ID] = Country.ID
  LEFT OUTER JOIN dbo.UserColderZIP
    ON UserColder.ID = UserColderZIP.UserColder
WHERE
  UserColder.ID NOT EXISTS (select [user id] from dbo.CountryUser where CountryUser.[User ID])

返回ID NOT某些表中的结果

2 个答案: