October 11, 2018

Sreekanth B

ValueLabs MySQL Most Frequently Asked Latest Interview Questions Answers

How database are managed?

Database is a collection of data and it is managed by a database server, which is a special program that is also known as MySQL database server. Application that you create usually communicates with the database server in the language which it can understand; mostly SQL language is used for communication. Database server in return interacts with the web server on same server or computer. Database server and web server result in the data which is being shown on the web.

What is required to create MYSQL database?

To create MySQL databse the first component which has to be present is a database server on which the queries of database will run and software tool through which you can access the applications. It also requires PHP scripts for communicating with the database using SQL commands.

What do you understand by MYSQL terminal?

MySQL terminal is used as a command line interface in many operating system. It provides a way to access the database and other resources using the SQL commands that are interpreted by the MySQL database server.

Why phpMyAdmin is used for MYSQL?

PhpMyAdmin is a very popular and easy to use GUI tool that can allow SQL commands to be run to create database, create tables, insert data and retrieve it. It provides a web based interface to the user for the ease of use. phpMyAdmin allows user to manage everything from one place and no other installation is required in the computer after this.
ValueLabs MySQL Most Frequently Asked Latest Interview Questions Answers
ValueLabs MySQL Most Frequently Asked Latest Interview Questions Answers

Write a query to create a database and a table?

MySQL comes up with some default database that can be used as a base to create a new one. The command that is used to create a new database is as follows:
CREATE DATABASE SQL command

The command has to be written in MySQL terminal. This command will create a new database and then you can create new tables and include data in it.

How can you make a database as your current database?

After making a database the first thing which has to be done is to create a table inside the database to test the new database that is being created. The command which is used to do that is:
USE aliendatabase;

This command allows us to make a database which is not a current database as my current. I have to just use the USE variable and the name of the database and it will become active for use.

What is the difference between a database and a table?

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

1. Tables are a way to represent the division of data in a database. Whereas, database is a collection of tables and data.
2. Tables group the data in relation with each other and create a dataset; this dataset will be used in the database. The data which are stored in the table in any form is a part of the database, but opposite is not true.

What Is Ddl, Dml And Dcl ?

If you look at the large variety of SQL commands, they can be divided into three large subgroups. Data Definition Language deals with database schemas and descriptions of how the data should reside in the database, therefore language statements like CREATE TABLE or ALTER TABLE belong to DDL. DML deals with data manipulation, and therefore includes most common SQL statements such SELECT, INSERT, etc. Data Control Language includes commands such as GRANT, and mostly concerns with rights, permissions and other controls of the database system.

How Do You Get The Number Of Rows Affected By Query?

SELECT COUNT (user_id) FROM users would only return the number of user_id’s.

If The Value In The Column Is Repeatable, How Do You Find Out The Unique Values?

Use DISTINCT in the query, such as SELECT DISTINCT user_firstname FROM users; You can also ask for a number of distinct values by saying SELECT COUNT (DISTINCT user_firstname) FROM users;

How Do You Return The A Hundred Books Starting From 25th?

SELECT book_title FROM books LIMIT 25, 100. The first number in LIMIT is the offset, the second is the number.

You Wrote A Search Engine That Should Retrieve 10 Results At A Time, But At The Same Time You'd Like To Know How Many Rows There're Total. How Do You Display That To The User?

SELECT SQL_CALC_FOUND_ROWS page_title FROM web_pages LIMIT 1,10; SELECT FOUND_ROWS(); The second query (not that COUNT() is never used) will tell you how many results there’re total, so you can display a phrase "Found 13,450,600 results, displaying 1-10". Note that FOUND_ROWS does not pay attention to the LIMITs you specified and always returns the total number of rows affected by query.

How Would You Write A Query To Select All Teams That Won Either 2, 4, 6 Or 8 Games?

SELECT team_name FROM teams WHERE team_won IN (2, 4, 6, 8)

How Would You Select All The Users, Whose Phone Number Is Null?

SELECT user_name FROM users WHERE ISNULL(user_phonenumber);

What Does This Query Mean: Select User_name, User_isp From Users Left Join Isps Using (user_id) ?

It’s equivalent to saying SELECT user_name, user_isp FROM users LEFT JOIN isps WHERE users.user_id=isps.user_id

How Do You Find Out Which Auto Increment Was Assigned On The Last Insert?

SELECT LAST_INSERT_ID() will return the last value assigned by the auto_increment function. Note that you don’t have to specify the table name.

What Does -i-am-a-dummy Flag To Do When Starting Mysql?

Makes the MySQL engine refuse UPDATE and DELETE commands where the WHERE clause is not present.
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