UNION ALL
operator is used to combine the result of two or more tables using SELECT
statement. The unique difference between UNION
and UNION ALL
operator is that UNION operator ignores the duplicate entries while combining the results while UNION ALL
doesn't ignore duplicate values.SELECT expression1, expression2, ... expression_n
FROM tables
[WHERE conditions]
UNION ALL
SELECT expression1, expression2, ... expression_n
FROM tables
[WHERE conditions];