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Please explain below query step by step and what does it mean?

in Databases 242 views

it is giving name of students securing 3rd highest marks

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It is giving name of student who secured 3rd rank among all.

Here are two columns "Name" and "marks" in the table. and "Count" column is just for explanation.

Name Marks Count
A 50 5
B 78 3
C 82 2
D 99 1
E 74 4

Here same table is referenced two times. S1 is for outer query and S2 for inner query. and both are co-related subqueries. Hence for each S1 we need to check all S2.

S1 = A,50 then count = 5 (Because 50 is lesser or equal to all given marks.)

S1 = B,78 then count = 3 (because 78 is lesser or equal to 78,82,99)

S1 = C,82 then count = 2 (because 82 is lesser or equal to 82,99)

S1 = D,99 then count = 1 (because nothing is lesser than 99 only it is equal to itself in S2.marks)

S1 = E,74 then count = 4 (because 74 is lesser or equal to 74,78,82,99)

Hence we have to choose name of count =3 Which giving name of student who secured 3rd rank.

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yes its 100% correct..

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