GATE CSE · Databases (DBMS) · Mock 2

employees has two columns that can each identify a row: id and email (if email were NOT NULL). What are they?

A student can have several phone numbers. In an ER diagram, Phone is a:

In InnoDB, which index stores the actual table rows in its leaf pages?

Meena has two orders, one with no amount. What does this return?

Adding an index or moving tables to faster disks without changing any application is an example of:

Which decompositions are lossless?

R(A, B, C, D) with FDs A → B, C → D

Which schedules are conflict serializable? (R = read, W = write, C = commit; the number is the transaction.)

R(A, B, C, D) has exactly one candidate key, A. How many super keys does R have?

Entities Student and Course are linked by an M:N relationship Enrols (with no other entities or multivalued attributes). What is the minimum number of tables needed?

Department and Employee are linked by a 1:N relationship WorksIn (one department, many employees). What is the minimum number of tables needed?

The list passed to NOT IN accidentally contains a NULL. What does this return?

Why do databases prefer B+ trees over B trees for indexes?

A view is defined as SELECT * FROM staff WHERE dept = 'Eng' WITH CHECK OPTION. What happens on UPDATE view SET dept = 'HR' WHERE id = 2?

Eight rows are split into three buckets. How big is each bucket?

R(A, B, C, D) has key AB and the FDs AB → C and B → D. What is the highest normal form of R?

Which schedules are cascadeless (no transaction reads uncommitted data)?

Which statements about two-phase locking (2PL) are true?

A disk block is 1024 bytes, a search key is 10 bytes and a block pointer is 6 bytes. What is the maximum order p (number of child pointers) of a B+ tree internal node?

How many different serial schedules are possible for 3 transactions?

Table R has 6 rows and table S has 4 rows. What is the maximum number of rows that R INNER JOIN S can return?