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asked in Databases by Boss (6.5k points) 8 117 248 | 88 views

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Lets take an example, Below are three instances of table with ratio of tuples equal to the original relation.

A B C
 Y  Y  L
 P  Q  M
 C  D  N
 X  Z  O

 

C D E
 L  Z  A
 M  Z  A
 N  Z  A
 L  Z  B
 M  Z  B
 O  Z  B

 

E F
 A  Z
 B  Z

If we join tem in any way the resulting table will have 6 tuples 
We can thus conclude that P join Q join R will result in 300 tuples.

A B C D E F
 Y  Y  L  Z  A  Z
 Y  Y  L  Z  B  Z
 P  Q  M  Z  A  Z
 P  Q  M  Z  B  Z
 C  D  N  Z  A  Z
 X  Z  O  Z  B  Z

 

answered by Active (2.4k points) 2 4 17
selected by
NO...if we join Q(CE) and R(E) then we can get 300 tuples.

Then with P....300 should be answer.
Suppose CE attributes have tuples as:

ab

ac

bb

bc

And EF attributes have tuples as:

bg

ct

Then the join of these results in tuples

abg

act

bct

bbg

Here we're getting the tuples from relation having maximum tuples. Correct me if I'm wrong @Rakesh
Thanks guys for correcting me, updated the answer with an example.
All credits to vaishali :)

Ths is wrongly framed question. They havent stated maximum or minimum.

If minumum, then its 0.

If maximum, then 300 tuples

^ how min = 0 ??

If one of C or E for all touple of relation Q is null ??
Consider the tables here:

 

               Table P

-------------------------------------------------

A          B       C

------------------------------------------------

1         1         1

2         2         2

.

.

200    200      200

 

          Table Q

------------------------------------

C            D              E

-------------------------------------

201         201            201

202         202            202

.

.

500         500            500

 

 

              Table R

------------------------------------------------

E                    F

------------------------------------------------

501              501

502              502

.

.

600              600
..........
@Vijay. I dont think that for relation Q, one of C or E can be null.
I thought, C in Q is foreign key pointng to C in P and similarly E in Q referring to E in R.

So, we should not consider foreign key even if there is common attribute between two relation unless it is mentioned explicitly. ??
@Vijay. Yes. We shouldn't consider unless explicitly stated because we have satisfied the conditions they have given.
But, if options are given, we need to consider that C is foreign key in Q   :P
....
maximum tupples can be 200.


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