Question

The sql standard prescribes three different types of __________ operations: left, right, and full.

Answer 1

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.