Join/inner join
An inner join, also known as a simple join, returns rows from joined tables that have matching rows. It does not include rows from either table that have no matching rows in the other.
SELECT * FROM cows_one INNER JOIN cows_two ON cows_one.cnumber =
cows_two.cnumber;
cnumber | cbreed | cnumber | breeds
------------+------------+----------+---------
2 | Guernsey | 2 | Jersey
3 | Angus | 3 | Brown Swiss
(2 rows)
The keyword inner is optional.