How to write “not in ()” sql query using join

问题:

Could some one please provide how to write following sql query using joins. I do not want use not in as well as if possible I would like to replace where condition as well.

SELECT d1.Short_Code
FROM domain1 d1
WHERE d1.Short_Code NOT IN (
  SELECT d2.Short_Code
  FROM Domain2 d2
)

I am using SQL Server 2008

回答1:

This article:

• NOT IN vs. NOT EXISTS vs. LEFT JOIN / IS NULL: SQL Server

may be if interest to you.

In a couple of words, this query:

SELECT  d1.short_code
FROM    domain1 d1
LEFT JOIN
        domain2 d2
ON      d2.short_code = d1.short_code
WHERE   d2.short_code IS NULL

will work but it is less efficient than a NOT NULL (or NOT EXISTS) construct.

You can also use this:

SELECT  short_code
FROM    domain1
EXCEPT
SELECT  short_code
FROM    domain2

This is using neither NOT IN nor WHERE (and even no joins!), but this will remove all duplicates on domain1.short_code if any.

回答2:

SELECT d1.Short_Code 
FROM domain1 d1
LEFT JOIN domain2 d2
ON d1.Short_Code = d2.Short_Code
WHERE d2.Short_Code IS NULL

回答3:

I would opt for NOT EXISTS in this case.

SELECT D1.ShortCode
FROM Domain1 D1
WHERE NOT EXISTS
    (SELECT 'X'
     FROM Domain2 D2
     WHERE D2.ShortCode = D1.ShortCode
    )