MySQL Interview Questions – Set 07

What are the security alerts while using MySQL?

Install antivirus and configure the operating system’s firewall.

Never use the MySQL Server as the UNIX root user.

Change the root username and password Restrict or disable remote access.

What is the difference between the database and the table?

There is a major difference between a database and a table. The differences are as follows:

Tables are a way to represent the division of data in a database while the database is a collection of tables and data.
Tables are used to group the data in relation to each other and create a dataset. This dataset will be used in the database. The data stored in the table in any form is a part of the database, but the reverse is not true.
A database is a collection of organized data and features used to access them, whereas the table is a collection of rows and columns used to store the data.

What is the heap table?

Tables that are present in memory is known as HEAP tables. When you create a heap table in MySQL, you should need to specify the TYPE as HEAP. These tables are commonly known as memory tables. They are used for high-speed storage on a temporary basis. They do not allow BLOB or TEXT fields.

What are DDL, DML, and DCL?

Majorly SQL commands can be divided into three categories, i.e., DDL, DML & DCL. Data Definition Language (DDL) deals with all the database schemas, and it defines how the data should reside in the database. Commands like CreateTABLE and ALTER TABLE are part of DDL.

Data Manipulative Language (DML) deals with operations and manipulations on the data. The commands in DML are Insert, Select, etc.

Data Control Languages (DCL) are related to the Grant and permissions. In short, the authorization to access any part of the database is defined by these.

Who owns MySQL?

MySQL is the most popular free and open-source database software which comes under the GNU General Public License. In the beginning, it was owned and sponsored by the Swedish company MySQL AB. Now, it is bought by Sun Microsystems (now Oracle Corporation), who is responsible for managing and developing the database.

How to change a password for an existing user via mysqladmin?

Mysqladmin -u root -p password “newpassword”.

What is InnoDB?

InnoDB is a storage database for SQL. The ACID-transactions are also provided in InnoDB and also includes support for the foreign key. Initially owned by InnobaseOY now belongs to Oracle Corporation after it acquired the latter since 2005.

How is the 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

How to delete columns in MySQL?

We can remove, drop, or delete one or more columns in an existing table using the ALTER TABLE statement as follows:

ALTER TABLE table_name DROP COLUMN column_name1, column_name2….;

What is MySQL Workbench?

MySQL Workbench is a unified visual database designing or GUI tool used for working on MySQL databases. It is developed and maintained by Oracle that provides SQL development, data migration, and comprehensive administration tools for server configuration, user administration, backup, etc. We can use this Server Administration to create new physical data models, E-R diagrams, and SQL development. It is available for all major operating systems. MySQL provides supports for it from MySQL Server version v5.6 and higher.

It is mainly available in three editions, which are given below:

  • Community Edition (Open Source, GPL)
  • Standard Edition (Commercial)
  • Enterprise Edition (Commercial)