UGC NET Computer Science Database Management Systems Previous Year Questions (PYQs) – Page 1 of 10

Typical DBMS query processing steps:

Scanning, parsing and validating → C

Query optimizer → A

Query code generator → D

Runtime database processor → B

Correct order:

C → A → D → B

In an unclustered B+ tree, retrieving records in sorted order requires scanning index entries and then fetching records from data pages.

Cost of scanning leaf level entries:

$F \times N$

Number of records:

$P \times N$

So, total cost:

$FN + PN = (F + P)N$

Final Answer: (b) (F + P) * N

A is correct because a database design is in BCNF when every relation schema in the design is in BCNF.

B is incorrect because BCNF removes dependency problems caused by non-super-key determinants.

C is correct because 3NF decomposition can be made lossless.

D is correct because 4NF deals with multivalued dependencies.

Find closure of $EC$:

$EC^+ = {E, C}$

Using $E \to A$,

$EC^+ = {E, C, A}$

Using $A \to B$,

$EC^+ = {E, C, A, B}$

Using $EC \to D$,

$EC^+ = {E, C, A, B, D}$

So, $EC$ determines all attributes.

A → False (only owner or DBA can grant privileges)

B → True

C → False (system error is not a malicious attack)

D → True

False statements:

A and C

In worst case, insertion causes splitting at every level.

There are 4 levels, so 4 new nodes may be created due to splitting.

If the root also splits, one extra new root node is created.

Maximum newly created nodes:

$4 + 1 = 5$

Relational algebra has the same expressive power as relational calculus only when relational calculus expressions are restricted to safe expressions.

Safe expressions ensure that the query result is finite and depends only on the database.

So,

Relational algebra is equivalent to domain relational calculus restricted to safe expressions.

Also,

Relational algebra is equivalent to tuple relational calculus restricted to safe expressions.

Therefore, $(c)$ and $(d)$ are correct.