Top Most MySQL Interview Questions and Answers

MySQL the most popular Open Source SQL database management system, is developed, distributed, and supported by MySQL AB(now acquired by Oracle).MySQL is a multi-threaded, multi-user SQL database management system and MySQL is written in C and C++ and its SQL parser is written in yacc.

Question 1: What are the technical features of MySQL?

MySQL database software is a client or server system which includes

Multithreaded SQL server supporting various client programs and libraries

Different backend

Wide range of application programming interfaces and Administrative tools.

Question 2: What are Heap tables?

HEAP tables are present in memory and they are used for high speed storage on temporary basis.

BLOB or TEXT fields are not allowed

Only comparison operators can be used =, <,>, = >,=<

AUTO_INCREMENT is not supported by HEAP tables

Indexes should be NOT NULL

Question 3: What are the advantages of MySQL when compared with Oracle?

MySQL is open source software which is available at any time and has no cost involved.

MySQL is portable

GUI with command prompt.

Administration is supported using MySQL Query Browser

Question 4: Differentiate between FLOAT and DOUBLE?

Following are differences for FLOAT and DOUBLE:

Floating point numbers are stored in FLOAT with eight place accuracy and it has four bytes.

Floating point numbers are stored in DOUBLE with accuracy of 18 places and it has eight bytes.

Question 5: What is BLOB?

BLOB stands for binary large object.

There are four types of BLOB based on the maximum length of values they can hold:

TINYBLOB

BLOB

MEDIUMBLOB

LONGBLOB

What is TEXT?

TEXT is case-insensitive BLOB. The four types of TEXT are:

TINYTEXT

TEXT

MEDIUMTEXT

LONGTEXT

Question 6: What is the difference between BLOB and TEXT?

In BLOB sorting and comparison is performed in case-sensitive for BLOB values.

In TEXT types sorting and comparison is performed case-insensitive.

Question 7: How is MyISAM table stored?

MyISAM table is stored on disk in three formats.

.frm file – storing the table definition

.MYD (MYData) – data file

.MYI (MYIndex) – index file