列出一个表中不在另一个表中的所有项目

Question

I have two tables in a database that I would like to compare. One is a list of inventory called stock and the other is a list of items ordered called items. I would like to list all inventory from the stock table that has never been ordered (so I basically want to check for any items that are in stock but NOT in items). I'm having some confusion because stock contains two keys, namely stock_num AND manu_code (code for manufacturer). Below is what I have so far, which I'm hoping is close or at least headed in the right direction. It presently returns an empty list with no errors.

select stock.stock_num, stock.manu_code, stock.description
from stock
        join items 
                on stock.stock_num = items.stock_num
                and stock.manu_code = items.manu_code
where items.stock_num and items.manu_code is null

Answer 1

Use LEFT OUTER JOIN :

select stock.stock_num, stock.manu_code, stock.description
from stock
left outer join items 
  on stock.stock_num = items.stock_num
  and stock.manu_code = items.manu_code
where items.stock_num is null and items.manu_code is null

Answer 2

Try this

select stock_num ,manu_code from  stock
except 
select stock_num,manu_code from items

you can get Which is not in Items Table

Refer : Except