Computer Knowledge

Database and SQL

3,929 Questions

Master structured query language commands, database joins, table constraints, and alias generation. This section covers relational database management concepts and query outputs essential for technical aptitude. These technical questions feature prominently in banking IT officer exams and computer knowledge sections.

SQL queries and aliasesDatabase table constraintsDatabase joins and transformationsStored procedures and functions

Database and SQL Questions

Multiple choice

Which query among following can give more than one name (employee name or ename)?

  1. SELECT ename WHERE ename AMONG ('value1', 'value2','value3', ...)

  2. SELECT ename WHERE ename = ('value1', 'value2','value3', ...)

  3. SELECT ename WHERE ename IN ('value1', 'value2','value3', ...)

  4. SELECT ename WHERE ename WITH ('value1', 'value2','value3', ...)

  5. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

IN will find any value existing in a set of candidates.

Multiple choice

Which of the following constraints is used in Oracle to prevent the duplication of values within the rows of specified column or a set of columns in a table?

  1. Domain integrity constraints

  2. Check constraints

  3. Unique constraints

  4. Referential integrity constraints

  5. Tuple constraints
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This constraint is used in Oracle to prevent the duplication of values within the rows of a specified column or a set of columns in a table.

Multiple choice

Which of the given statements is/are true? P : Foreign key cannot have a null value. Q : The primary key and foreign key can exist in a same relation. R : Foreign key relation is known as target relation.

  1. Q only

  2. P only

  3. Both P and Q

  4. Both P and R

  5. R only
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is true choice. Q statement is correct because the primary key and the foreign key can exist in the same relation. Moreover foreign key can refer to the primary key in the same relation.So, this is a correct choice.

Multiple choice

Which of the following statements is/are correct? P : Candidate key cannot be null. Q : If the primary key is composed of more than one attribute, then these attributes are known as super attributes. R : All the candidate keys can be primary keys.

  1. P only

  2. Both P and Q

  3. Both P and R

  4. Both Q and R

  5. All of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Option P is correct because a candidate key is a key that uniquely identifies a row in a relation. So, this cannot be null as it uniquely identifies a row. Option R is correct because primary key is chosen from a set of candidate keys. In other words all the candidate keys are the candidates for the primary key. So, in this way all the candidate keys are primary keys. So, this is the correct answer.