SQL Examples

Question 1

How to implement cartesian product in SQL?

Question 2

What are some of the string operations in SQL?

Question 3

How is “in” operator used in SQL?

Question 4

What is a Sub Query?

Question 5

What are Nested Subqueries?

Question 6

How are subqueries in the Where clause formed?

Question 7

How is set comparison operator “Some” clause used in SQL?

Question 8

How is set comparison operator “all” clause used in SQL?

Question 9

How and why is a “exists” clause and “not exists” used?

Question 10

How to test for absence of duplicate tuples using “Unique” clause?

Question 11

How are subqueries in the From clause formed?

Question 12

How is SQL “With” clause used?

Question 13

How are subqueries in the Select clause formed?

Question 14

How to delete tuples from a table in SQL?

Question 15

How to insert tuples into a table in SQL?

Question 16

How to update a tuple in SQL?

Question 17

How is the conditional statement “CASE” used in SQL?

Question 18

What are the different types of joins between relations?

Question 19

What is “inner join”?

Question 20

What is “outer join”?

Question 21

What is “Left Outer Join”?

Question 22

What is “Right Outer Join”?

Question 23

What is “Full Outer Join”?

Question 24

What is “Self Join”?

Question 25

What is a view?

Question 26

How to define a view in SQL?

Question 27

What are composition of views in SQL? aka View Expansion

Question 28

How to update a view?

Question 29

What are materialized views?

Question 30

What are Transactions?

Question 31

What are integrity Constraints? Give examples

Question 32

What is referential integrity?

Question 33

What are cascading actions in referential integrity?

Question 34

What are SQL Data types?

Question 35

How to create an Index in SQL?

Question 36

How to create a User Defined data type in SQL?

Question 37

What are domains? and how to create domains in SQL?

Question 38

What are the Authorization Specifications in SQL? What are the previleges in SQL?

Question 39

How to revoke authorizations in SQL?

Question 40

What are Roles in SQL? how are they created?

Question 41

What are triggers?

Answer 41

A trigger defines a set of actions that are performed in response to an insert, update,
or delete operation on a specified table

To design a trigger mechanism, we must:
◦ Specify the events / (like update, insert, or delete) for the trigger to executed
◦ Specify the time (BEFORE or AFTER) of execution
◦ Specify the actions to be taken when the trigger executes

There are two types of triggers based on the level at which the triggers are applied:

1.Row level triggers
2.Statement level triggers

Used for logging, Auditing users and their actions, adding additional values to a table, simple validataion.

Adding triggers is often seen as faster and easier than adding code to an application,
but the cost of doing so is compounded over time with each added line of code

Question 42

Property of aggregate functions with respect to null values

Answer 42

Except count(*) all other aggregate functions ignore NULL Values

Question 43

What is the difference between where clause and having clause

Answer 43

In where clause you cannot use aggregate functions.. normally group by clause is executed before having clause and so aggregate functions could be used on having clause

Question 44

What does Check integrity constraint mean ?

Answer 44

It is set while creating the table and is enforced whenever data is added

Age INT CHECK(Age>18)

Question 45

What character is used to signify space while using like clause

Answer 45

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