SQL Database Concepts Interview Question:

Explain what is the difference between UNION and UNION ALL?

Submitted by: Administrator

UNION selects only distinct values whereas UNION ALL selects all values and not just distinct ones.

UNION: SELECT column_names FROM table_name1
UNION
SELECT column_names FROM table_name2
UNION All: SELECT column_names FROM table_name1
UNION ALL
SELECT column_names FROM table_name2
Submitted by: Administrator