Below are the Latest question frequently asked by IT HR , Kindly have a look.
1) What is MySQL?
MySQL is a multithreaded, multi-user SQL database management system which has more than 11 million installations. This is the world’s second most popular and widely used open source database. It is interesting how MySQL name was given to this query language. The term My is coined by the name of the daughter of co-founder Michael Widenius`s daughter, and SQL is the short form of Structured Query Language. Using MySQL is free of cost for the developer, but enterprises have to pay a license fee to Oracle.
Formerly MySQL was initially owned by a for-profit firm MySQL AB, then Sun Microsystems bought it and then Oracle bought Sun Microsystems, so Oracle currently owns MySQL.
MySQL is an Oracle-supported Relational Database Management System (RDBMS) which is based on structured query language. MySQL supports wide ranges of operating systems most famous of those include Windows, Linux & UNIX. Although it is possible to develop a wide range of application with MySQL, it is only used for web applications & online publishing. It is a fundamental part of an open source enterprise known as Lamp.
What is Lamp?
Lamp is a platform used for web development. Lamp uses Linux, Apache, MySQL, and PHP as an operating system, web server, database & object-oriented scripting language respectively. And hence abbreviated as LAMP.
2) In which language MySQL has been written?
MySQL is written in C and C++, and its SQL parser is written in yacc.
3) What are the technical specifications of MySQL?
MySQL has the following technical specifications –
- Flexible structure
- High performance
- Manageable and easy to use
- Replication and high availability
- Security and storage management
- Graphical Tools
- MySQL Enterprise Monitor
- MySQL Enterprise Security
- JSON Support
- Replication & High-Availability
- Manageability and Ease of Use
- OLTP and Transactions
- Geo-Spatial Support
4) What is the difference between MySQL and SQL?
SQL is known as the standard query language. It is used to interact with the database like MySQL. MySQL is a database that stores various types of data and keeps it safe.
A PHP script is required to store and retrieve the values inside the database.
SQL is a computer language, whereas MySQL is a software or an application
SQL is used for the creation of database management systems whereas MySQL is used to enable data handling, storing, deleting and modifying data
5) What is the difference between database and 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 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 the reverse is not true.
- A database is a collection of organized data and also features which are used to access them, whereas table is a collection of rows and columns which are used to store the data.
6) Why do we use the MySQL database server?
First of all MYSQL server is free to use for developers and a small fee for enterprises.
MySQL server is open source.
The community of MySQL is tremendous and supportive hence any help regarding MySQL is resolved as soon as possible.
MySQL has very stable versions available, as MySQL has been in the market since a long time so all bugs arising in the previous builds have been continuously removed and a very stable version is provided after every update.
The MySQL database server is very fast, reliable and easy to use. You can easily use and modify the software. MySQL software can be downloaded free of cost from the internet.
7) What are the different tables present in MySQL?
There are many tables that remain present by default. But, MyISAM is the default database engine used in MySQL. There are five types of tables that are present:
- INNO DB
8) What is the difference between CHAR and VARCHAR?
A list of differences between CHAR and VARCHAR:
- CHAR is variable-length whereas VARCHAR is of fixed length.
- CHAR and VARCHAR types are different in storage and retrieval.
- CHAR column length is fixed to the length that is declared while creating a table. The length value ranges from 1 and 255.
- When CHAR values are stored when they are right-padded using spaces to a specific length. Trailing spaces are removed when CHAR values are retrieved.
- CHAR uses static memory allocation whereas VARCHAR uses dynamic memory allocation.
- CHAR is 50% faster than VARCHAR.
9) What is the difference between TRUNCATE and DELETE in MySQL?
TRUNCATE is a DDL command, DELETE is a DML command.
It is not possible to use Where command with TRUNCATE but you can use it with DELETE command.
TRUNCATE cannot be used with indexed views whereas DELETE can be used with indexed views.
The DELETE command is used to delete data from a table. It only deletes the rows of data from the table while, truncate is very dangerous command and should be used carefully because it deletes every row permanently from a table.
10) How many Triggers are possible in MySQL?
There are only six Triggers allowed to use in MySQL database.
- Before Insert
- After Insert
- Before Update
- After Update
- Before Delete
- After Delete