test series

Question

Question: 11   Consider the following ORACLE relations: One (x, y) = {<2, 5>, <1, 6>, <1, 6>, <1, 6>, <4, 8>, <4, 8>} Two (x, y) = {<2, 55>, <1, 1>, <4, 4>, <1, 6>, <4, 8>, <4, 8>, <9, 9>, <1, 6>} Consider the following two SQL queries SQ1 and SQ2 : SQ1: SELECT * FROM One) EXCEPT (SELECT * FROM Two); SQ2: SELECT * FROM One EXCEPT ALL (SELECT * FROM Two); For each of the SQL queries, what is the cardinality (number of rows) of the result obtained when applied to the instances above ?

1.  1 and 2 respectively   2. 2 and 2 respectively   3. 2 and 1 respectively   4.  1 and 1 respectively

 

i'm not getting the second query. what does except all will make a difference from except?

according to me both will give the same answer.

please explain. 

Comments

that is for particular tuple,

<2,5> is m=1, n=0 ===> EXCEPT ALL = 1

<1,6> is m=3, n=2 ===> EXCEPT ALL = 1

<4,8> is m=2, n=2 ===> EXCEPT ALL = 0

---

ya i meant for <1,6> only..got it..thanks :)

---

SQ1: SELECT * FROM One) EXCEPT (SELECT * FROM Two);

The result will be : 

        x      y

        2     5

Number of rows = 1.

 

SQ2: SELECT * FROM One EXCEPT ALL (SELECT * FROM Two);

The result will be: 

        x      y

         2     5

         1      6

Number of rows = 2.