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.