In this blog, we are going to see the difference between Union and Union All in SQL with example "Union All" will not eliminate duplicate rows instead it will pull all the rows. "Union" removes the duplicate records by issuing "Select Distinct" on the result set. Union SQL: select '1234' Emplid ,'Name1' Name from Dual union select '1234' Emplid ,'Name1' Name from Dual Result: EMPLID NAME 1234 Name1 Union All SQL: select '1234' Emplid ,'Name1' Name from Dual union all select '1234' Emplid ,'Name1' Name from Dual Result: EMPLID NAME 1234 Name1 1234 Name1 I hope this explains the difference between Union and Union All. If you have any questions, please post it in the comments section.