MySQL mcq questions and answers | MySQL MCQs Page-2 section-6

Section 1 Section 2 Section 3 Section 4 Section 5 Section 6 Section 7 Section 8 Section 9 Section 10 Section 11 Section 12

11.

Which of the following use 'NULL' to indicate failure?

mysql_init(), mysql_real_connect()

A. 0

B. 1

C. 2

D. 3

Answer & Solution Discuss in Board Save for Later

12.

Consider a database name "db_name" whose attributes are intern_id (primary key), subject, subject_value.
Intern_id = {1, 2, 3, 4, 5, 6}
Subject = {sql, oop, sql, oop, c, c++}
Subject_value = {0, 0, 1, 1, 2, 2, 3, 3}
If these are one to one relation then what will be the output of the following MySQL statement?

SELECT intern_id
FROM db_name
WHERE subject IN (SELECT subject FROM db_name WHERE subject_value IN (3, 2));

A. {5, 6}

B. {1, 2, 3}

C. {3, 4}

D. {1, 2, 3, 4, 5, 6}

Answer & Solution Discuss in Board Save for Later

Answer & Solution

Answer: Option D

Solution:

This question is about understanding how to use SQL queries to retrieve data from a database. Let's break down the code step by step:
1. Database Structure
Imagine a table named "db_name" which stores information about interns. This table has three columns:
* intern_id: A unique identifier for each intern (primary key). * subject: The subject the intern is studying (like SQL, OOP, etc.). * subject_value: A numerical value associated with the subject.
2. Understanding the Query
The provided SQL query is designed to find intern IDs based on specific subject values.
* SELECT intern_id: This part tells the database to retrieve the intern_id column.
* FROM db_name: This indicates that the data should be taken from the "db_name" table.
* WHERE subject IN (SELECT subject FROM db_name WHERE subject_value IN (3, 2)): This is the core of the query. It's a nested query: * Inner Query: `SELECT subject FROM db_name WHERE subject_value IN (3, 2)` - This query first selects the "subject" column from "db_name" where the subject_value is either 3 or 2. * Outer Query: `SELECT intern_id FROM db_name WHERE subject IN (...)` - This query then selects the intern_id from "db_name" where the subject matches the subjects found in the inner query. 3. Applying the Data
Let's apply the data given in the question to the query:
* Inner Query: * The inner query finds subjects with subject_value of 3 or 2, which are "c" and "c++".
* Outer Query: * The outer query then searches for intern IDs where the subject is "c" or "c++", resulting in intern_id 5 and intern_id 6. 4. The Answer
The output of the SQL query will be {5, 6}. Therefore, the correct answer is Option A.

13.
The datatype INT stores . . . . . . . .

A. 16 bit

B. 32 bit

C. 48 bit

D. 64 bit

Answer & Solution Discuss in Board Save for Later

14.
When linking to a static MySQL C client library, the client library and the client application must use the same compiler option.

A. True

B. False

Answer & Solution Discuss in Board Save for Later

15.
Which of the following returns an SQLSTATE code?

A. mysql_error()

B. mysql_errno()

C. mysql_sqlstate()

D. mysql_close()

Answer & Solution Discuss in Board Save for Later

16.
What is the command to see the warning messages?

A. DISPLAY WARNINGS

B. DISP WARNINGS

C. DISP WARNING

D. SHOW WARNINGS

Answer & Solution Discuss in Board Save for Later

17.
Which keyword used with UNION retains duplicate rows?

A. ALL

B. NARROW

C. STRICT

D. DISTINCT

Answer & Solution Discuss in Board Save for Later

18.
The ALL subquery performs which operation?

A. row

B. column

C. table

D. database

Answer & Solution Discuss in Board Save for Later

19.
UPDATE statement is a DML statement. What does DML stand for?

A. Data Manipulation Language

B. Data Manipulation Level

C. Data Markup Language

D. Data Markup Level

Answer & Solution Discuss in Board Save for Later

20.
What is the default size of 'max_binlog_cache_size' system variable?

A. 1 GB

B. 2 GB

C. 4 GB

D. 8 GB

Answer & Solution Discuss in Board Save for Later

1 2 3 4 5 6 7 8 9 10

11.
Which of the following use 'NULL' to indicate failure?

`mysql_init(), mysql_real_connect()`

Answer & Solution

Answer & Solution

13.
The datatype INT stores . . . . . . . .

Answer & Solution

14.
When linking to a static MySQL C client library, the client library and the client application must use the same compiler option.

Answer & Solution

15.
Which of the following returns an SQLSTATE code?

Answer & Solution

16.
What is the command to see the warning messages?

Answer & Solution

17.
Which keyword used with UNION retains duplicate rows?

Answer & Solution

18.
The ALL subquery performs which operation?

Answer & Solution

19.
UPDATE statement is a DML statement. What does DML stand for?

Answer & Solution

20.
What is the default size of 'max_binlog_cache_size' system variable?

Answer & Solution

Read More Section(MySQL Miscellaneous)

MySQL mcq questions and answers | MySQL MCQs

11. Which of the following use 'NULL' to indicate failure? mysql_init(), mysql_real_connect()

Answer & Solution

Answer & Solution

13. The datatype INT stores . . . . . . . .

Answer & Solution

14. When linking to a static MySQL C client library, the client library and the client application must use the same compiler option.

Answer & Solution

15. Which of the following returns an SQLSTATE code?

Answer & Solution

16. What is the command to see the warning messages?

Answer & Solution

17. Which keyword used with UNION retains duplicate rows?

Answer & Solution

18. The ALL subquery performs which operation?

Answer & Solution

19. UPDATE statement is a DML statement. What does DML stand for?

Answer & Solution

20. What is the default size of 'max_binlog_cache_size' system variable?

Answer & Solution

Read More Section(MySQL Miscellaneous)

11.
Which of the following use 'NULL' to indicate failure?

`mysql_init(), mysql_real_connect()`

13.
The datatype INT stores . . . . . . . .

14.
When linking to a static MySQL C client library, the client library and the client application must use the same compiler option.

15.
Which of the following returns an SQLSTATE code?

16.
What is the command to see the warning messages?

17.
Which keyword used with UNION retains duplicate rows?

18.
The ALL subquery performs which operation?

19.
UPDATE statement is a DML statement. What does DML stand for?

20.
What is the default size of 'max_binlog_cache_size' system variable?