UNION Vs UNION ALL: SQL Operators For Combining Datasets

Difference Between UNION and UNION ALL in SQL

UNION and UNION ALL are SQL operators used to combine the results of two or more SELECT statements. While they serve similar purposes, they differ in how they handle duplicate rows.


  
  
  1. UNION

Combines the results of two or more SELECT statements into a single result set.
Automatically removes duplicate rows from the result set.

Sorting: Performs an implicit DISTINCT operation to remove duplicates, which can make it slower for large datasets.

  
  
  Syntax:


SELECT column1, column2
FROM table1
UNION
SELECT column1, column2
FROM table2...