As SQL does not treat a relation as a set, duplicate tuples can appear. To eliminate these, the DISTINCT keyword is used.
SELECT SALARY FROM EMPLOYEE
-- { 1200, 1400, 1400, 1600 }
SELECT DISTINCT SALARY FROM EMPLOYEE
-- { 1200, 1400, 1600 }As SQL does not treat a relation as a set, duplicate tuples can appear. To eliminate these, the DISTINCT keyword is used.
SELECT SALARY FROM EMPLOYEE
-- { 1200, 1400, 1400, 1600 }
SELECT DISTINCT SALARY FROM EMPLOYEE
-- { 1200, 1400, 1600 }