sqlpostgresqlexceptsql-except

EXCEPT it exits in 2 other tables

I need to get all values from table product , EXCEPT they exits in 2 other table products. Is this query acceptable using 2 EXCEPTS ? Should this be done differently . 

CREATE table missing_values
AS
select post
from product
EXCEPT
select post
from product_table_a
EXCEPT
select post
from product_table_b
;
Solution

  • A - B - C is the same as A - (B + c):

    SELECT post
FROM product
EXCEPT
(
  SELECT post
  FROM product_table_a
  UNION ALL
  SELECT post
  FROM product_table_b
) AS sum;