获取表1中但不在表2中的产品

Question

I have a table with 8 thousand products (table 1) and another table in which I have to manually add the products (table 2), I would like to know how many products I need to add, I have a key in the two tables to identify each product.

Table 1 - code_table1
A1001
A1002
A1003
A1004
A1005
A1006

Table 2 - code_table2
A1001
A1002
A1003
A1004

The problem is that in table 1 the column that has the key is called code_table1 and in table 2 the column that has the key is called code_table2

Expected result:

Products to add: 2
Keys to add:
A1005
A1006

You can help me with the consultation to obtain the mentioned thing, thanks in advance!

Answer 1

select * from table1 where code_table1 not in (
  select code_table2 from table2
);