I'm a newbie, just learning SQL and have this question: I have two tables with the same columns. Some registers are in the two tables but others only are in one of the tables. To illustrate, suppose table A = (1,2,3,4), table B=(3,4,5,6), numbers are registers. I need to select all registers in table B if they are not in table A, that is result=(5,6). What query should I use? Maybe a join. Thanks.
Add a comment
|
2 Answers
You can either use a NOT IN query like this:
SELECT col from A where col not in (select col from B)
or use an outer join:
select A.col
from A LEFT OUTER JOIN B on A.col=B.col
where B.col is NULL
The first is easier to understand, but the second is easier to use with more tables in the query.
Comments
Select register from TABLE_B b
Where not exists (Select register from TABLE_A a where a.register = b.register)
I assumed you have a column named register in TABLE_A and TABLE_B
1 Comment
user994432
logically i think it works, i will have to try with my tables with 1000+ registers... thanks!!
