Exclude columns from Minus operations in oracle sql - sql

Question

I'd like to know if you can exclude a column from a MINUS operation
For example:
select column 1, column 2, column 3
from table 1
minus
select column 1, column 2
from table 2;
while column 3 is excluded from the operation.
Is there anyway to do that?
Thank you

Answer 1

You have a few alternatives.
#1
Minus without column3 then rejoin result to the original table to get the missing values for column3.
select *
from (
select column1, column2
from table1
minus
select column1, column2
from table2
)
join table1 using (column1, column2)
#2
Use an ANTI-JOIN the NOT EXISTS clause should work the same as NOT IN anyway.
select column1, column2, column3
from table1
where (column1, column2) not in (
select column1, column2
from table2
)

Answer 2

Perhaps you are after this?
select table1.column1, table1.column2, table1.column3
from table1
left table2 on table1.column1 = table2.column1 and table1.column2 = table2.column2
where table1.id IS NULL
This will result in only those table1 records that do not have matching column1 and column2 values in table2.

Answer 3

Look at this:
with t(a, b, c) as (
select 1, 2, 3 from dual union all
select 2, 2, null from dual union all
select 2, 3, 5 from dual
), t1(a, b) as (
select 1, 2 from dual union all
select 2, 2 from dual union all
select 2, 3 from dual
), t2 as (
select a, b, c from t
minus
select a, b, null from t1
)
select a, b from t2
A B
-----
1 2
2 3
SQLFiddle
If you have null values in your column3 and you want to escape them you can escape them like this:
with t(a, b, c) as (
select 1, 2, 3 from dual union all
select 2, 2, null from dual union all
select 2, 3, 5 from dual
), t1(a, b) as (
select 1, 2 from dual union all
select 2, 2 from dual union all
select 2, 3 from dual
), t3 as (
select a, b, nvl(c, -1) from t
minus
select a, b, null from t1
)
select a, b from t3
A B
-----
1 2
2 2
2 3
SQLFiddle