Answer Posted / elumalai d

--QUESTION36:-What is different between union and minus?

UNOIN:- it returns all the records from both tables without duplicates.
Example:-
A={1,2,3,4}
B={2,3,4,5,6}
AUB={1,2,3,4,5,6}

CREATE TABLE question36 (empid NUMBER);
CREATE TABLE quest36 (empid NUMBER);

INSERT INTO question36 VALUES(1);
INSERT INTO question36 VALUES(2);
INSERT INTO question36 VALUES(3);
INSERT INTO question36 VALUES(4);

INSERT INTO quest36 VALUES(2);
INSERT INTO quest36 VALUES(3);
INSERT INTO quest36 VALUES(4);
INSERT INTO quest36 VALUES(5);
INSERT INTO quest36 VALUES(6);
COMMIT;

SELECT empid FROM question36
UNION
SELECT empid FROM quest36;

DELETE FROM question36;
DELETE FROM quest36;
COMMIT;

MINUS:- it returns table A values not available in table B.
Example:-
A={1,2,3,4}
B= {2,3,5}
A-B={1,4}

INSERT INTO question36 VALUES(1);
INSERT INTO question36 VALUES(2);
INSERT INTO question36 VALUES(3);
INSERT INTO question36 VALUES(4);

INSERT INTO quest36 VALUES(2);
INSERT INTO quest36 VALUES(3);
INSERT INTO quest36 VALUES(5);
COMMIT;

SELECT empid FROM question36
MINUS
SELECT empid FROM quest36;

DROP TABLE question36;
DROP TABLE quest36;

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