SQL

SQL UNION ALL Operator

SELECT age
FROM Teachers
UNION ALL
SELECT age
FROM Students;

SQL UNION Operator

SELECT column_name(s) FROM table1
UNION
SELECT column_name(s) FROM table2;

union all query in sql

SELECT * from employee
UNION
SELECT * from students

union vs union all in sql

UNION ALL:
COMBINES THE RESULT OF 2 QUERY AND
DOESN'T REMOVE DUPLICATE ROWS
AND DOESN'T SORT BY FIRST COLUMN

UNION:
COMBINES THE RESULT OF 2 QUERY AND
REMOVES DUPLICATE ROWS AND
SORTS BY FIRST COLUMN 

union all in sql

UNION ALL:
COMBINES THE RESULT OF 2 QUERY AND
DOESN'T REMOVE DUPLICATE ROWS
AND DOESN'T SORT BY FIRST COLUMN