Consider the following relation: R (A B C) A primary key with 100 tuples. S (E F G) E primary key with 50 tuples. T (AE D) AE primary key with 80 tuples. U (D G H) H primary key with 10 tuples.
The maximum number of possible records in the result of _______.

A cartesian product of two tables will be returned.This is because when we perform any JOIN operation on two tables a cartesian product of those tables is performed and then based on any select condition in WHERE clause the resultant rows are returned.But here as there are no common columns the process stops after cartesian product.

after R join S we have all 5000 different combination of A E in our new table say 1

now 1 join T will give 80 different combination present in T, how – as A E is key in T which will be compared with all possible combination of AE in best case our all 80 will match and will give 80 tuples , now name the result relation as 2

now key point for max tuples - for max tuples always think of duplicate values of common attribute in the relation in which our common attribute is not key .

here G is not key attribute in our both tables (2 and U ) so we can duplicates its value in any of the table for max number of tuple, now your aptitude will come in handy (think on your own now if possible)

2 join U = we have 80 tuples in 2 for maximum match i’m assuming all the G values are same (say 0) and also in U all G values are 0.when our 2’s G is compare with U’s G .

1st tuple of 2 matches with all of U because both have G as 0 and give u 10 tuples

for every 80 tuples there will be 10 tuples in join so resultant table will have 800 tuples.