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Sql Objective Questions - 56

Questions on Index, Insert, Primary key, Inner joines, Outer Joines, Delete, Union, Operators, Update, Having Clause, Truncate, Candiate Key & Constraint etc.

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Question: 1

How many Primary key a table can max have?

(A) Depends on no of Columns
(B) Only 2
(C) Only 1
(D) Depends on DBA

Level: Beginner Category: Syntax
[Posted by: Admin | Chicago, USA]

Question: 2

Which of the following is not Constraint in SQL?

(A) Primary Key
(B) Not Null
(C) Check
(D) Union

Level: Beginner Category: Syntax
[Posted by: Admin | Chicago, USA]

Question: 3

Which operator is used to match text while search?

(A) IN
(B) LIKE
(C) BETWEEN
(D) IS

Level: Beginner Category: Like
[Posted by: Admin | Chicago, USA]

Question: 4

Which of the following operator select a range of data between two values?

(A) IN
(B) BETWEEN
(C) %
(D) OR

Level: Beginner Category: Between
[Posted by: Admin | Chicago, USA]

Question: 5

Why use Full Join in sql?

(A) Return rows when there is at least one match in both tables
(B) Return all rows from the left table, even if there are no matches in the right table
(C) Return all rows from the right table, even if there are no matches in the left table
(D) Return rows when there is a match in one of the tables

Level: Practionar Category: Joins
[Posted by: Admin | Chicago, USA]

Question: 6

Sql supports single line comment, which of the following is single line comment?

(A) '
(B) "
(C) //
(D) --

Level: Beginner Category: Syntax
[Posted by: Admin | Chicago, USA]

Question: 7

Indexes speed up SELECT's and slow down INSERT's

(A) True
(B) False

Level: Practionar Category: Syntax
[Posted by: Admin | Chicago, USA]

Question: 8

A Primary Key is a column or a combination of columns that uniquely identify a record. Only one Candidate Key can be Primary Key

(A) True
(B) False

Level: Beginner Category: Syntax
[Posted by: Admin | Chicago, USA]

Question: 9

A Candidate Key can be any column or a combination of columns that can qualify as unique key in database. There can be multiple Candidate Keys in one table. Each Candidate Key can qualify as Primary Key

(A) True
(B) False

Level: Beginner Category: Syntax
[Posted by: Admin | Chicago, USA]

Question: 10

Which of the following is the correct order of occurrence in a typical SQL statement?

(A) select, group by, where, having
(B) select, where, having, group byselect, having, where, group by
(C) select, having, where, group by
(D) select, where, group by, having

Level: Practionar Category: Syntax
[Posted by: Admin | Chicago, USA]

Question: 11

Which of the following is true for a primary key?

(A) It can take a value more than once
(B) It can’t take null values
(C) It can take null values
(D) None of these

Level: Beginner Category: Syntax
[Posted by: Admin | Chicago, USA]

Question: 12

Difference between a primary key and a unique key?

(A) Primary key cannot be a date variable whereas unique key can be
(B) Primary key can take null values but unique key cannot null values
(C) You can have only one primary key whereas you can have multiple unique keys
(D) None of the above

Level: Practionar Category: Syntax
[Posted by: Admin | Chicago, USA]

Question: 13

Which of the following is true for TRUNCATE in SQL?

(A) It is usually slower than DELETE command
(B) There is no comparison between DELETE & TRUNCATE
(C) It is usually faster than DELETE command
(D) None of these

Level: Beginner Category: Syntax
[Posted by: Admin | Chicago, USA]

Question: 14

Which of the following command(s) is /  are related to transaction control in SQL?

(A) COMMIT
(B) ROLLBACK
(C) SAVEPOINT
(D) All of the these

Level: Beginner Category: Syntax
[Posted by: Admin | Chicago, USA]

Question: 15

Which of the following statement(s) is/are true for UPDATE in SQL?

1. You can update only a single table using UPDATE command
2. You can update multiple tables using UPDATE command
3. In UPDATE command, you must list what columns to update with their new values (separated by commas).
4. To update multiple targeted records, you need to specify UPDATE command using the WHERE clause.

(A) 1, 3 and 4
(B) 2, 3 and 4
(C) 3 and 4
(D) 1 only

Level: Practionar Category: Syntax
[Posted by: Admin | Chicago, USA]

Question: 16

Which of the following statement is correct about ‘CREATE TABLE’ command while creating a table?

(A) We need to assign a datatype to each column
(B) We have flexibility in SQL. We can assign a datatype to column even after creating a table
(C) It is mandatory to insert atleast a single row while creating a table
(D) None of the above

Level: Beginner Category: Syntax
[Posted by: Admin | Chicago, USA]

Question: 17

What are the various levels of constraints?

Constraints are the representation of a column to enforce data entity and consistency. There are two levels  of a constraint, namely:

1. column level constraint
2. table level constraint

Level: Beginner Category: Syntax
[Posted by: Admin | Chicago, USA]

Question: 18

What is the difference between ‘HAVING’ CLAUSE and a ‘WHERE’ CLAUSE?

Ans: 
HAVING clause can be used only with SELECT statement. It is usually used in a GROUP BY clause and whenever GROUP BY is not used, HAVING behaves like a WHERE clause. 

Having Clause is only used with the GROUP BY function in a query whereas WHERE Clause is applied to each row before they are a part of the GROUP BY function in a query.

Level: Beginner Category: Syntax
[Posted by: Admin | Chicago, USA]

Question: 19

Which of the following data type is/are used for Date &  Time?

(A) Datetimeoffset
(B) Date
(C) Time
(D) All of the Above

Level: Beginner Category: Syntax
[Posted by: Admin | Chicago, USA]

Question: 20

Which data type is used to store binary data upto 2,147,483,647?

(A) Text
(B) Image
(C) Blob
(D) None of the Above

Level: Practionar Category: Syntax
[Posted by: Admin | Chicago, USA]

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