Term: UNION

Definition:
The UNION operator is used to combine the result-set of two or more SELECT statements.

UNION Requirements:

Each SELECT statement within the UNION must have the exact same number of columns
The columns must also have similar data types.
The columns in each SELECT statement must be in the exact same order.

Example Syntax:

SELECT column_name(s) FROM table1

UNION

SELECT column_name(s) FROM table2;