The sql standard prescribes three different types of JOIN operations: left, right, and full.
The LEFT [OUTER] JOIN yields all rows with matching values in the join columns, plus all of
the unmatched rows from the
left
table.
The RIGHT [OUTER] JOIN yields all rows with matching values in the join columns, plus all of
the unmatched rows from the
right
table.
The FULL [OUTER] JOIN yields all rows with matching values in the join columns, plus all the
unmatched rows from both tables named in the FROM clause.
