sql union all or union code example

Example 1: sql union

Combines the results from 2 or more SELECT statements and returns only
distinct values.
Example: Returns the cities from the events and subscribers tables.
SELECT city FROM events
UNION
SELECT city from subscribers;

Example 2: union all in sql

UNION ALL:
COMBINES THE RESULT OF 2 QUERY AND
DOESN'T REMOVE DUPLICATE ROWS
AND DOESN'T SORT BY FIRST COLUMN