CREATE TABLE tb1(ID int) 

CREATE TABLE tb2(ID int)

BEGIN  TRAN
DECLARE @i INT = 500
WHILE @i > 0
begin
INSERT INTO dbo.tb1
VALUES  ( @i  -- v - int
          )
SET @i = @i -1
end
COMMIT

我测试的时候tb1 是1000，tb2 是500

 DBCC FREESYSTEMCACHE ('ALL','default');

SET STATISTICS IO ON
SET STATISTICS TIME on
SELECT * FROM tb1 EXCEPT SELECT * FROM tb2;
SELECT * FROM tb1 WHERE id NOT IN(SELECT id FROM tb2);--得不到任何值
 SET STATISTICS IO OFF
SET STATISTICS TIME OFF

SELECT * FROM tb1 EXCEPT SELECT * FROM tb2;
|--Merge Join(Right Anti Semi Join, MERGE:([master1].[dbo].[tb2].[ID])=([master1].[dbo].[tb1].[ID]), RESIDUAL:([master1].[dbo].[tb1].[ID] = [master1].[dbo].[tb2].[ID]))
       |--Sort(DISTINCT ORDER BY:([master1].[dbo].[tb2].[ID] ASC))
       |    |--Table Scan(OBJECT:([master1].[dbo].[tb2]))
       |--Sort(DISTINCT ORDER BY:([master1].[dbo].[tb1].[ID] ASC))
            |--Table Scan(OBJECT:([master1].[dbo].[tb1]))

SELECT * FROM tb1 WHERE id NOT IN(SELECT id FROM tb2);--得不到任何值
  |--Hash Match(Right Anti Semi Join, HASH:([master1].[dbo].[tb2].[ID])=([master1].[dbo].[tb1].[ID]), RESIDUAL:([master1].[dbo].[tb1].[ID]=[master1].[dbo].[tb2].[ID]))
       |--Table Scan(OBJECT:([master1].[dbo].[tb2]))
       |--Nested Loops(Left Anti Semi Join)
            |--Nested Loops(Left Anti Semi Join, WHERE:([master1].[dbo].[tb1].[ID] IS NULL))
            |    |--Table Scan(OBJECT:([master1].[dbo].[tb1]))
            |    |--Top(TOP EXPRESSION:((1)))
            |         |--Table Scan(OBJECT:([master1].[dbo].[tb2]))
            |--Row Count Spool
                 |--Table Scan(OBJECT:([master1].[dbo].[tb2]), WHERE:([master1].[dbo].[tb2].[ID] IS NULL))