SQL Server - NOT IN

*爱你&永不变心* 提交于 2019-11-30 07:59:00
Dave Markle

It's because of the way NOT IN works.

To avoid these headaches (and for a faster query in many cases), I always prefer NOT EXISTS:

SELECT  *  
FROM Table1 t1 
WHERE NOT EXISTS (
    SELECT * 
    FROM Table2 t2 
    WHERE t1.MAKE = t2.MAKE
    AND   t1.MODEL = t2.MODEL
    AND   t1.[Serial Number] = t2.[serial number]);

You're probably better off comparing the fields individually, rather than concatenating the strings.

SELECT t1.*
    FROM Table1 t1
        LEFT JOIN Table2 t2
            ON t1.MAKE = t2.MAKE
                AND t1.MODEL = t2.MODEL
                AND t1.[serial number] = t2.[serial number]
    WHERE t2.MAKE IS NULL
SELECT [T1].*
FROM [Table1] AS [T1]
WHERE  NOT EXISTS (SELECT 
    1 AS [C1]
    FROM [Table2] AS [T2]
    WHERE ([T2].[MAKE] = [T1].[MAKE]) AND
        ([T2].[MODEL] = [T1].[MODEL]) AND
        ([T2].[Serial Number] = [T1].[Serial Number])
);
Imtiaz
SELECT  *  FROM Table1 
WHERE MAKE+MODEL+[Serial Number]  not in
    (select make+model+[serial number] from Table2 
     WHERE make+model+[serial number] IS NOT NULL)

That worked for me, where make+model+[serial number] was one field name

Use a LEFT JOIN checking the right side for nulls.

SELECT a.Id
FROM TableA a
LEFT JOIN TableB on a.Id = b.Id
WHERE b.Id IS NULL

The above would match up TableA and TableB based on the Id column in each, and then give you the rows where the B side is empty.

One issue could be that if either make, model, or [serial number] were null, values would never get returned. Because string concatenations with null values always result in null, and not in () with null will always return nothing. The remedy for this is to use an operator such as IsNull(make, '') + IsNull(Model, ''), etc.

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