union all return values of two tables including duplicates, union return two tables values omit duplicates

The main difference between union All statement and Union is Union All statement is much faster then union. Because Union all statement does not look for duplicate rows, but on the other hand union statement does not look for duplicate rows, where or not exist.

Union is remove the duplicate rows.Union All is Show the all rows

Union : it fetches the unique record, here datatype and number of columns from two tables should be same Union All :it fetches the all records,here also datatype and number of columns from two tables should be same

Union All includes all rows where as Union includes only unique rows. duplicate rows has get removed in Union Query

union returns distinct Rows. union all returns all Rows.

union = it will display the records without duplication union all = it will display the records with duplication

union returns distinct Rows. union all returns all Rows.

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Union returns only distinct rows while Union ALL return all rows. Union All is faster than Union because it does not have to eliminate duplicate rows.

Union and union all are used to combine the output of two queries.When using these we have to keep in mind the number of columns and type of columns should be identical.Union returns distinct records whereas union all returns duplicate also.Union all works on Text data type also but union doesnot.

Union returns only distinct rows while Union ALL return all rows. Union All is faster than Union because it does not have to eliminate duplicate rows.

union statement returns distinct results where as union all statement returns duplicate records as well.Union All is faster in performance since it does not eliminate duplicate records.