Introduction to MySQL Interview Questions and Answers
MySQL is basically an open-sourced and one of the most commonly used Relational Database Management System (RDBMS). It provides its extensive support and compatibility towards Linux, macOS, Windows operating systems. It is mainly one of the most common extensions of SQL. It is the central component of a LAMP (Linux, Apache, MySQL and Perl/PHP/Python) and is written in C and C++. Some of the important features are mentioned below:
- It supports DDL (Data definition language) with respect to InnoDB Storage Engine
- It provides support to Information Schema
- There is SSL support present
- It has an embedded database library
- It has built-in replication support
- It provides cross-platform support.
Now, if you are looking for a job which is related to MySQL then you need to prepare for the MySQL Interview Questions. It is true that every interview is different as per the different job profiles but still to clear the interview you need to have a good and clear knowledge of MySQL processes. Here, we have prepared the important MySQL Interview Question and answers which will help you get success in your interview.
Below are the 10 important MySQL Interview Questions and answers that are frequently asked in an interview. These questions are divided into two parts are as follows:
Part 1 – MySQL Interview Questions (Basic)
This first part covers basic Interview Questions and Answers
Q1. What do you mean by MySQL Workbench?
Answer:
MySQL Workbench is basically the officially integrated environment for MySQL. It is implemented to graphically control the MySQL and visually design database structures. It basically gives users the provision to control the functionalities as per their requirements. It is mainly available in two versions, one is the open source free community edition and the other one is the proprietary standard edition.
Q2. Explain MySQL Database Workbench?
Answer:
MySQL Database Workbench is basically the software application which has been used to develop and administrate different relational databases using SQL. It has been developed by Upscene Productions. It provides the support to the below mentioned relational databases:
- MySQL Database
- Microsoft SQL Server
- Oracle Databases
- Nexus DB
- Inter Base
- SQL Anywhere
Q3. What do you mean my Joins and explain different types of MySQL Joins?
Answer:
In MySQL, joins are basically used to fetch the records from two or more table using some interconnected common fields or keys among the selected tables. There are mainly three types joins present in MySQL.
a. Inner Join: In case of inner join, it is used to fetch the list of rows when there is a match among the specified tables. It is the default join type. Syntax for the same is given below: Syntax: SELECT column_name(s)
FROM table1 INNER JOIN table2
ON table1.column_name = table2.column_name;
b. Left Join: In case of left join, it returns all rows from the left table even if there is no match in the right table.
Syntax: SELECT column_name(s)
FROM table1 LEFT JOIN table2
ON table1.column_name = table2.column_name;
c. Right Join: In case of right join, it returns all rows from the right table even if there is no match in the left table.
Syntax: SELECT column_name(s)
FROM table1 RIGHT JOIN table2
ON table1.column_name = table2.column_name;
Q4. Explain different types of MySQL functions?
Answer:
This is the basic MySQL Interview Questions asked in an interview. Find below the different types of functions used in MySQL.
- MySQL String Functions: Examples are- INSERT, CONCAT, FORMAT, INSERT, LENGTH, LEFT, FIELD, LTRIM, TRIM, UPPER etc.
- MySQL Numeric Functions: Examples are- AVG, DIV, EXP, MAX, MIN, POWER, TRUNCATE etc.
- MySQL Date Functions: Examples are – ADDDATE, ADDTIME, DATE, MONTH, MINUTE etc.
- MySQL Advanced Functions: Examples are – BIN, CASE, CAST, DATABASE, IF, ISNULL, VERSION etc.
Q5. Explain the differences between primary key and foreign key constraint?
Answer:
A primary key constraint is used to uniquely identify every record in a table. It always contains unique values and never contains any NULL values. Below is the syntax for the same whereas foreign key constraint is used to link between two tables. It is basically the field which refers to the primary key of the other table.
Part 2 – MySQL Interview Questions (Advanced)
Let us now have a look at the advanced Interview Questions.
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Q6. Explain the differences between delete, drop and truncate?
Answer:
Find below the basic differences:
Delete: Delete is a DML statement and it can be implemented using ‘where’ clause and can also be rolled back. Syntax: DELETE FROM table_name WHERE column_name = column_value;
Drop: Drop is a DDL statement and it can’t be rolled back. By using this, the entire table and all its constraints and privileges will be removed. Syntax: DROP TABLE table_name;
Truncate: Truncate is a DDL statement and it is used to remove all the rows from a table but its structures, constraints, and indexes will remain as it is. Syntax: TRUNCATE TABLE table_name;
Q7. Explain the main difference between InnoDB and MyISAM?
Answer:
In the case of InnoDB, it is used to store the tables in tablespace whereas, in the case of MyISAM, it stores each MyISAM table in a separate file.
Q8. Explain different types of tables in MySQL?
Answer:
Find below different types of a table in MySQL.
- InoDB: This type of table is mainly used to enhance and support transaction using COMMIT and ROLLBACK commands.
- HEAP: This type of table is mainly used to process data access in a more faster than the normal speed. But on the downside of it, all data will be lost in case of table deletion.
- BDB: This type of table is also used for transaction support implemented using COMMIT command but its processing speed is much slower than that of InoDB.
Q9. Explain MySQL transaction properties?
Answer:
This is the most asked MySQL Interview Questions asked in an interview. The transactions mainly consist of four properties.
- Atomicity: The property is mainly used to control all the operations and ensure all the transactions get completed successfully.
- Consistency: This ensures the database changes according to the successfully committed transactions.
- Isolation: This is basically used to control the independent transactions.
- Durability: This is used to control and measure the effect and presence of committed transactions in case of system or database failure.
Q10. Explain few pros and cons of MySQL?
Answer:
Below are few important pros and cons:
Pros:
- The MySQL products are more stable and solid compared to its competitors
- It is easier to use from the user experience perspective
- It is open source and thus is free to use.
- There is large and extensive community support exists for MySQL
Cons:
- There is sometimes a bit performance scaling issues exists in case of MySQL
- Sometimes development progress gets lagged due to lacking of community development approach.
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