MySQL Interview Questions and Answers
MYSQL is one of the most successful and leading pathways toward data administration careers. You will be amazed to know that this database service holds a total of 46.83% share in the relational database market. So to make your career and prepare for interviews in this field would be a good choice. Today we will help with these interviews by providing you with some MYSQL Interview Questions and Answers. MYSQL is one of the most popular database technologies used in the database industry. Popular companies like Microsoft, Amazon, Oracle, and IBM are using this technology on a vast basis to manage and store their data. According to one survey, nowadays more than 90% of organizations are using OSDBMS i.e. Open Source Database Management System. But to handle this database, professionals must know the MYSQL programming language.
|Quick Facts About MySQL
|What is the latest version of MySQL?
|8.0.22 released in 19th October 2020
|When was MySQL first released?
|23 May 1995
|Who developed MySQL?
|What language does MySQL use?
|C and C++ language
|GNU Public License
MySQL Query Interview Questions
The MySQL aggregate function performs a calculation on a set of values, and it returns a single value as output. It ignores NULL values when it performs calculation except for the COUNT function.
MySQL provides many aggregate functions that are listed below.
- MAX() etc
|The function returns the single value which is anyhow mandatory.
|The procedure returns zero or N values.
|They only work with a statement: Select
|They can work with multiple statements: Insert, Update, Delete, Select.
|In function, transactions are not possible
|In the procedure, transactions are possible
|Error handling is not possible
|With try-catch, error handling is possible.
In Mysql, joins are used to retrieve data from multiple tables. It is performed whenever two or more tables are joined.
There are three types of MySQL joins:-
- MySQL INNER JOIN
SELECT columns FROM table_1 INNER JOIN table_2 ON table_1.column = table_2.column;
- MySQL LEFT JOIN
SELECT columns FROM table_1 LEFT JOIN table_2 ON table_1.column = table_2.column;
- MySQL RIGHT JOIN
SELECT columns FROM table_1 RIGHT JOIN table_2 ON table_1.column = table_2.column;
- CHAR can have a maximum of 255 characters, but VARCHAR can hold a maximum of 65,535 characters.
- CHAR field is a fixed length, but VARCHAR is a variable length field.
- CHAR uses static memory allocation, but VARCHAR uses dynamic memory allocation.
We can use
SELECT std_id, COUNT(std_id) as cnt FROM Student GROUP by std_id having cnt > 1
SELECT id, name, department FROM Employee where MOD(id,2) = 1
The stored procedure is like a subprogram in a typical computing language which is stored in the database. A stored procedure contains the name, list of parameters, and the SQL statements. All the relational database system works as pillars for stored procedures.
In this example, we are creating a simple procedure called job_data, when this procedure will get executed, all the data from "jobs" tables will get displayed.
CREATE PROCEDURE GetAllPages()
SELECT * FROM pages WHERE title LIKE '%MySQL Interview Questions%';
SELECT * FROM Student where MOD(id,2) = 0
SELECT * FROM 'TableName' WHERE 'status' = 1 LIMIT 10
In MYSQL Database, data is stored in tabular form and that is why we also call it a Relational Database Management System. With the help of it, users can develop an infinite number of applications but it is mainly used for web applications. Talking about platforms, it can run on various platforms like LINUX, UNIX, and WINDOWS and is reliable, fast, and very easy to use. We hope these questions will help you to clear your core concepts regarding MYSQL. Let us help you with some short and important tips which might help you with your interviews-
- MYSQL is a programming language, so always avoid YES and NO answers.
- If you don’t know the answer, simply say I don't know rather than pretending you know.
- Always carry a pen and notepad with you.
- If you are stuck somewhere don’t panic, just stay calm and think out loud.
- Go with the expectation that you will reject a lot, as “Failure is the key to Success”.