Top 25 MySQL Interview Questions And Answers (2021)

MySQL is a multithreaded, multi-user SQL database management system which has more than 11 million installations. This MySQL interview questions guide will help you clear the interview and help you get your dream job in MySQL Programming.   the most popular MySQL interview questions that are commonly asked in the interviews by experts. Top MySQL Interview Questions and Answers .

Q1.What is the full form of SQL?

A. Structured Query List
B. Structure Query Language
C. Sample Query Language
D. None of these.

Option B – Structure Query Language

Q2.Which of the following is not a DDL command?

A.TRUNCATE
B. ALTER
C. CREATE
D. UPDATE

Option D – UPDATE

Q3.Which of the following are TCL commands?

A. COMMIT and ROLLBACK
B. UPDATE and TRUNCATE
C. SELECT and INSERT
D. GRANT and REVOKE

Option A – COMMIT and ROLLBACK

Q4.SQL Views are also known as

A. Simple tables
B. Virtual tables
C. Complex tables
D. Actual Tables

Option B – Virtual tables

Q5.Which datatype can store unstructured data in a column?

A. CHAR
B. RAW
C. NUMERIC
D. VARCHAR

Option B – RAW

Q6.Which of the following is not Constraint in SQL?

A. Primary Key
B. Not Null
C. Check
D. Union

Option D – Union

Q7.How many Primary keys can have in a table?

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

Option A – Only1

Q8.Which data manipulation command is used to combines the records from one or more tables?

A. SELECT
B. PROJECT
C. JOIN
D. PRODUCT

Option c – JOIN

Q9.In which of the following cases a DML statement is not executed?

A. When existing rows are modified.
B. When a table is deleted.
C. When some rows are deleted.
D. All of the above

Option B – When a table is deleted.

Q10.Which of the following statement is true?

A. TRUNCATE free the table space while DELETE does not.
B. Both TRUNCATE and DELETE statements free the table’s space.
C. Both TRUNCATE and DELETE statement does not free the table’s space.
D. DELETE free the table space while TRUNCATE does not.

Option A – TRUNCATE free the table space while DELETE does not.

Q11.What is returned by INSTR (‘JAVAT POINT’, ‘P’)?

A. 6
B. 7
C. POINT
D. JAVAT

Option B – 7

Q12.Which of the following is also called an INNER JOIN?

A. SELF JOIN
B. EQUI JOIN
C. NON-EQUI JOIN
D. None of the above

Option B – EQUI JOIN

Q13._ clause creates temporary relation for the query on which it is defined.

A. WITH
B. FROM
C. WHERE
D. SELECT

Option A – With

Q14._ command makes the updates performed by the transaction permanent in the database?

A. ROLLBACK
B. COMMIT
C. TRUNCATE
D. DELETE

Option B – COMMIT

Q15.How can you change “Thomas” into “Michel” in the “LastName” column in the Users table?

A. UPDATE User SET LastName = ‘Thomas’ INTO LastName = ‘Michel’
B. MODIFY Users SET LastName = ‘Michel’ WHERE LastName = ‘Thomas’
C. MODIFY Users SET LastName = ‘Thomas’ INTO LastName = ‘Michel’
D. UPDATE Users SET LastName = ‘Michel’ WHERE LastName = ‘Thomas’

Option D – UPDATE Users SET LastName = ‘Michel’ WHERE LastName = ‘Thomas’

Q16.Which type of JOIN is used to returns rows that do not have matching values?

A. Natural JOIN
B. Outer JOIN
C. EQUI JOIN
D. All of the above

Option B – Outer JOIN

Q17.A CASE SQL statement is __?

A. A way to establish a loop in SQL.
B. A way to establish an IF-THEN-ELSE in SQL
C. A way to establish a data definition in SQL
D. All of the above.

Option B – A way to establish an IF-THEN-ELSE in SQL

Q18.Which statement is true regarding procedures?

A. They include procedural and SQL statements.
B. They work similarly to the functions.
C. It does not need unique names.
D. It cannot be created with SQL statements.

Option A – They include procedural and SQL statements.

Q19.Group of operations that form a single logical unit of work is known as

A. View
B. Network
C. Unit
D. Transaction

Option D – Transaction

Q20.Shared locks are applied while performing

A. Read operations
B. Write operations
C. A & B both
D. None of the above

Option A – Read operations

Q21.A sequence in SQL can generate a maximum number:

A. 39 digits
B. 38 digits
C. 40 digits
D. 37 digits

Option B – 38 digits

Q22.What is the difference between a PRIMARY KEY and a UNIQUE KEY?

A. Primary key can store null value, whereas a unique key cannot store null value.
B. We can have only one primary key in a table while we can have multiple unique keys
C. Primary key cannot be a date variable whereas unique key can be
D. None of these

Option B – We can have only one primary key in a table while we can have multiple unique keys

Q23.Which operator is used to compare the NULL values in SQL?

A. Equal
B. IN
C. IS
D.None of Above

Option C – Is

Q24.__ is NOT a type of constraint in SQL language?

A. FOREIGN KEY
B. PRIMARY KEY
C. UNIQUE
D. ALTERNATE KEY

Option D – ALTERNATE KEY

Q25.Which statement is used to get all data from the student table whose name starts with p?

A. SELECT * FROM student WHERE name LIKE ‘%p%’;
B. SELECT * FROM student WHERE name LIKE ‘p%’;
C. SELECT * FROM student WHERE name LIKE ‘_p%’;
D. SELECT * FROM student WHERE name LIKE ‘%p’;

Option B – SELECT * FROM student WHERE name LIKE ‘p%’;

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