What the difference between UNION and UNIONALL?

Question

Prashant K · Answer

Both commands combines the tables with common fields except ‘UNION’ displays all the rows from objects without looking at duplicate records whereas ‘UNION ALL’ looks for it and displays only unique records. Thus ‘UNION’ it slower than ‘UNION ALL’

Anonymous User · Answer

Union will remove the duplicate rows from the result set while Union All doesn’t.

interview

What the difference between UNION and UNIONALL?

Can you answer this question?

2 Answers