Consider a database name “interveiwmania” whose attributes

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Consider a database name “interveiwmania” whose attributes are internid (primary key), subject, subjectvalue.
Internid = {1, 2, 3, 4, 5, 6}
Subject = {sql, oop, sql, oop, c, c++}
Subjectvalue = {0, 0, 1, 1, 2, 2, 3, 3}
If these are one to one relation then what will be the output of the following query?
```
SELECT internid
FROM interveiwmania
WHERE subject IN (SELECT subject FROM interveiwmania WHERE subjectvalue = 3);
```

1. {1, 2, 3}
2. {3, 4}
3. {5, 6}
4. All of above
5. None of these

Correct Option: C

Only those value will be selected whose subjects are c and c++. In the sub query subjectvalue=3 which belongs to subject {c, c++} after that this subject belong to internid {5, 6).