sql-server-2008 - in sql inserting from one table to another without dupes

Question

this worked once before for me but the script is not working now i want toinsert into another table but without any dupes......

 select * from [Data_Guru].[dbo].[MORTGAGE_AUG_27_new_1] 
 where Phone not in (select Phone from [dbo].MASTER_LIST)

that is the bottom part that i am having trouble with when i change it to another table it shows all of the numbers that are not in that table. and i do know for a fact that there shouldnt be many if any duplicate records in the 2 tables.. they are complete different categories....pleas help

Answer 1

通常，“in”和“not in”查询的问题是 NULL 的存在。尝试这个：

select *
from [Data_Guru].[dbo].[MORTGAGE_AUG_27_new_1]
where Phone not in (select Phone from [dbo].MASTER_LIST where Phone is not null) 

Answer 2

select distinct * from [Data_Guru].[dbo].[MORTGAGE_AUG_27_new_1] t1
where NOT EXISTS (select Phone from [dbo].MASTER_LIST where t1.phone=t2.phone)