10 Important MySQL Interview Questions

MySQL Interview Question

Do you have a MySQL interview coming up? Here are 10 MySQL interview questions you must know.

MySQL is an open-source relational database management system (RDBMS) used by millions across the globe. It provides extensive support and compatibility for Linux, macOS, and Windows operating systems. MySQL is an extension of SQL. It is the central component of a LAMP stack (Linux, Apache, MySQL, and Perl/PHP/Python) and is written in C and C++.

1. What do you mean by MySQL workbench?

MySQL workbench is the official integrated environment for MySQL. It allows you to graphically control the MySQL setup and visually design database structures. The workbench gives users the provision to control MySQL functionalities as per their requirements. It is available in two versions: an open-source community edition (available for free) and a proprietary standard edition (paid).

2. What is MySQL database workbench?

MySQL database workbench is the software application used to develop and administrate different relational databases using SQL. It has been developed by Obscene Productions. The database workbench supports the following relational databases:

  • MySQL Database.
  • Microsoft SQL Server.
  • Oracle Databases.
  • Nexus DB.
  • Inter Base.
  • SQL Anywhere.

3. What do you mean by joins? What are the different types of MySQL joins?

Joins are used to fetch records from two or more tables using common fields or keys among the selected tables. There are three types of joins in MySQL:

Inner Join: It is used to return rows only when there is a match among the tables involved. It is the default join type. The syntax for inner join is:

SELECT column_name(s)
FROM table1 INNER JOIN table2
ON table1.column_name = table2.column_name;

Left Join: In case of left join, it returns all rows from the left table (table1) even if there is no match in the right table (table2). The syntax for left join is:

SELECT column_name(s)
FROM table1 LEFT JOIN table2
ON table1.column_name = table2.column_name;

Right Join: In case of right join, it returns all rows from the right table (table2) even if there is no match in the left table (table1). The syntax for right join is:

Syntax: SELECT column_name(s)
FROM table1 RIGHT JOIN table2
ON table1.column_name = table2.column_name;

4. What are the different types of MySQL functions?

Database interview questions and answers, particularly MySQL interview questions, include the topic of functions. The following types of functions are used in MySQL:

  • MySQL String Functions: INSERT, CONCAT, FORMAT, INSERT, LENGTH, LEFT, FIELD, LTRIM, TRIM, and UPPER.
  • MySQL Numeric Functions: AVG, DIV, EXP, MAX, MIN, POWER, and TRUNCATE.
  • MySQL Date Functions: ADDDATE, ADDTIME, DATE, MONTH, and MINUTE.
  • MySQL Advanced Functions: BIN, CASE, CAST, DATABASE, IF, ISNULL, and VERSION.

The list is exhaustive. Visit the official MySQL documentation portal for more functions.

5. What is the difference between primary key and foreign key constraints?

A primary key constraint is used to uniquely identify every record in a table. It always contains unique values and never contains any NULL value. Whereas the foreign key constraint is used to link two tables. The foreign key field in one table is the primary key field of another table.

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6. What are delete, drop, and truncate commands?

  1. Delete: Delete is a DML statement and can be implemented using the ‘where’ clause. It can also be rolled back. Delete removes only those rows from the table which meet the ‘where’ condition. Syntax: DELETE FROM table_name WHERE column_name = column_value;
  2. Drop: Drop is a DDL statement and can’t be rolled back. By using this, the entire table and all of its constraints and privileges will be removed. Syntax: DROP TABLE table_name;
  3. Truncate: Truncate is a DDL statement. It is used to remove all the rows from a table while retaining its structures, constraints, and indexes. Syntax: TRUNCATE TABLE table_name;

7. What is the difference between InnoDB and MyISAM?

InnoDB is used to store the tables in a tablespace, whereas MyISAM stores each MyISAM table in a separate file.

Click here to go to the MySQL Official Documentation Website.

8. What are the different types of tables in MySQL?

  • InnoDB: This type of table is used to enhance and support transactions using COMMIT and ROLLBACK commands.
  • HEAP: This type of table is used to access data faster than the normal speeds. But on the downside, 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 InnoDB.

9. What are the transaction properties in MySQL?

This is one of the most frequently asked MySQL interview questions. MySQL transactions consist of four properties:

  • Atomicity: The property controls all the operations and ensure all the transactions get completed successfully.
  • Consistency: This property ensures that the database changes occur only after successfully committed transactions.
  • Isolation: This property ensures that the transactions function independent of each other.
  • Durability: It is used to control and measure the effect and presence of committed transactions in case of system or database failures.

10. What are some pros and cons of MySQL?

Some advantages of using MySQL are:

  • MySQL products are more stable and solid compared to its competitors.
  • MySQL is easier to use from user experience perspective.
  • It is open-source and free to use.
  • Large and extensive community support exists for MySQL.

Some disadvantages of using MySQL are:

  • Performance scaling issues exist in MySQL.
  • Development progress lags at times due to the lack of community development approach.

Have you appeared for a MySQL based interview before? Do you work with MySQL everyday? Are you aware of other important MySQL interview questions? We’d love to know in the comments.

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