Multiple Queries with a Single ResultSet

How to merge multiple queries and produce a single result set??

1. UNION:

Union helps to merge Two Queries but on the condition that,

• Both queries return the same number of columns
• The selected columns in both queries have matching data type

Incorrect Union Mapping

Correct Union Mapping

2. JOINS:

Joins can be used when both the queries have a mapping column to match and fetch result set.