Answer / rahul gaikwad

Let's consider the difference between Minus and Union using
following examples.

1.create TABLE A AND B With similar structure
2.insert records in Table A and B.
3.Keep some records identical(here 2 rows).
4.find out the difference betwn 2 looking into the output.


CREATE TABLE A(NAME VARCHAR2(30));
INSERT INTO A VALUES('A');
INSERT INTO A VALUES('B');
INSERT INTO A VALUES('C');
INSERT INTO A VALUES('D');
COMMIT;

CREATE TABLE B(NAME VARCHAR2(30));
INSERT INTO b VALUES('A')
INSERT INTO b VALUES('B')
INSERT INTO b VALUES('Y')
INSERT INTO b VALUES('X')
COMMIT;



1) SELECT * FROM A
MINUS
SELECT * FROM B

NAME
------------------------------
C
D
2 rows selected



2)SELECT * FROM A
UNION
SELECT * FROM B


NAME
------------------------------
A
B
C
D
Y
x
6 rows selected

Answer / humayun quaiser

unoin:- This operator returns from all the queries(combined
through union) but not duplicate record will be display.
ex- A={1,2,3,4}
B={2,3,4,5}
AUB={1,2,3,4,5}............

Minus:- This operator displays records which belongs to only
the first query.
ex:- A={1,2,3,4}
B= {2,3,5}
A-B={1,4}...................

Answer / varma

union:
Union combines result set of two select statements
into one result set and from the result it eliminates
duplicate rows.

Minus:
Minus takes the result set of one select statement
and removes those rows that are also returned by another
select statement.

Answer / bhaskar

UNION : Union combines the two table records, its eliminates
the duplicate records

Minus: ???

Answer / pravin

Union combines the two table records, its eliminates
the duplicate records. while minus shows only those rows
which are not dulicated of table first in query.

Answer / ajinkyasingh bais

The SQL UNION clause/operator is used to combine the results of two or more SELECT statements without any duplicate rows.
whereas
The SQL MINUS clause/operator is used to combine two SELECT statements,but returns rows only from the first SELECT statement that are identical to a row in the second SELECT statement

Answer / elumalai d

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;

EMPID
---------
1
2
3
4
5
6

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;

EMPID
---------
1
4

DROP TABLE question36;
DROP TABLE quest36;

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