This tutorial is for all the aspirants who want to crack an entry-level interview for MySQL Developer Role.
The pre-requisite for this tutorial is a basic understanding of MySQL, MySQL server, structured query language, and hands-on experience in MySQL query solving.
Interview Questions for Entry-Level MySQL Developer
Try to come up with your own answers, later you can refer to the answers given in the descriptions.
1. What is MySQL?
MySQL is the most popularly used relational database management system or RDBMS. It is maintained, distributed, and developed by Oracle Corporation. The first version of MySQL was released in May 1995.
The advantages of using MySQL are as follows:
- MySQL is open-source: This means the code of MySQL is available to the public, which makes it customizable, this gives users the benefit of customizing it as they require per their requirements.
- MySQL is free to use: MySQL provides various versions, majorly, there are two types: Community Version and Paid Version. The community version is free for all. However, the paid version offers additional resources. Both versions fully support development requirements.
- MySQL is scalable: MySQL is highly scalable, which means it can support multiple users with the help of threads.
- MySQL is easy to use: Among various RDBMS, MySQL is considered one of the easy-to-use RDBMS.
- Strong community: MySQL has a strong community, which means that there is a large bunch of people using MySQL, therefore, it’s easy to find solutions to problems in MySQL.
2. What is MySQL Server?
MySQL server is responsible for providing querying, data structures, and connectivity capabilities to the database management system. It also includes integration capabilities with many different platforms and helps in working in a high-demand production environment such as huge database management, data analytics, etc.
3. What are MySQL clients and their utilities?
There are several MySQL clients, a few of them are listed below:
- MySQL: It is a simple shell statement for input line editing such as SQL statements or batch file execution.
- Mysqladmin: It is a client to perform administrative operations, such as database manipulation, flushing tables to disk, etc.
- Mysqldump: It is a client used for dumping MySQL databases as SQL statements or in tab-separated format into a file.
- Mysqlcheck: It is a client for table maintenance to check, analyzed, repair, and optimize tables.
4. Mention the types of relationships present in MySQL?
In MySQL, there are three types of relationships between two tables:
- One-to-one: One-to-one relationship means that a record present in table 1 has one and only one record matching with table 2 and vice versa. Let’s take an example of a student and the student identity number. In this case, each student will have only one student identity number associated with it and likewise, a student number will only be associated with a single student.
- One-to-many: One-to-many relationship means that a record in table 1 can have associations with multiple records in table 2. For example, a teacher can teach multiple subjects.
- Many-to-many: Many-to-many relationship means that records in table 1 and table 2 can have multiple associations in both tables. For example, a table of books and authors. Now, an author can write multiple books and a book can be written by multiple authors.
5. How to create a table in MySQL?
To create a table in MySQL, CREATE TABLE statement is used. For example:
CREATE TABLE tablename (value1 datatype, value2 datatype,...);Code language: SQL (Structured Query Language) (sql)
6. How will you insert values in a Database in MySQL?
INSERT INTO table statement is used to insert rows in a table. There are two ways using which you can add values to a table:
1. Insert rows with all the values-
INSERT INTO tablename(field1, field2, field3) VALUES (value1, value2, value3);Code language: SQL (Structured Query Language) (sql)
2. Insert a row with specific or selective values-
INSERT INTO tablename VALUES (value1, value2, value3);Code language: SQL (Structured Query Language) (sql)
What is the difference between DELETE and TRUNCATE commands?
Both DELETE and TRUNCATE commands are used for deleting the data in a table but there is a small difference between the two.
The DELETE command is used for deleting the whole table and its data. This means it is used to delete both the data and the schema of a table. On the other hand, the TRUNCATE command is used to delete only the data of the table, i.e., the rows in the table. It does not remove the schema of the table.
Because of this difference, the DELETE command is a little slower than the TRUNCATE command.
What is the difference between DDL, DML, DCL, and TCL?
1. DDL: DDL stands for Data Definition Language. This language is for creating and altering a table. This language consists of the mentioned commands- CREATE, ALTER, DROP, RENAME, TRUNCATE and COMMENT
2. DML: DML stands for Data Manipulation Language. This language is used for the manipulation of data within a database. It comprises of the mentioned commands- SELECT, INSERT, UPDATE, DELETE and MERGE.
3. DCL: DCL stands for Data Control Language. This language is used for providing and revoking access from the users. It comprises of two commands- GRANT and REVOKE.
4. TCL: TCL stands for Transaction Control Language. This language is used for controlling the transaction of all the queries. It includes the mentioned commands- COMMIT, REVOKE, and SAVEPOINT.
5. DQL: DQL stands for Data Query Language. This language is used for querying the database. It includes the SELECT command.
What is an index in MySQL? How to create it in MySQL?
Indexes are used when there’s a huge database. For querying through a large database indexes are used. Using index users can access data quickly.
Below is the syntax for creating an index for a table:
CREATE INDEX indexname ON tablename (column1, column3,..);Code language: SQL (Structured Query Language) (sql)
//To create a unique index CREATE UNIQUE INDEX indexname ON tablename (column1, column4...);Code language: SQL (Structured Query Language) (sql)
What is BLOB in MySQL?
A BLOB stands for the binary large object in SQL. A BLOB is a datatype that is used for storing variable amounts of data. This data type is basically used for storing images, media files, PDFs, etc. There are four types of BLOB datatype: TINYBLOB, BLOB, MEDIUMBLOB, and LONGBLOB. Below is an example of how you can create a table that has a BLOB-type variable in it:
CREATE TABLE photo(ID INT, Name VARCHAR(20), Image BLOB, ALT VARCHAR(40));Code language: SQL (Structured Query Language) (sql)
Can you create users in MySQL? If yes, how can you do that?
Yes, we can create users in MySQL. We can create users in MySQL with the help of CREATE USER statement.
CREATE USER 'username'@'hostname' IDENTIFIED BY password;Code language: SQL (Structured Query Language) (sql)
What is a view? How to create a view?
When we are working with a huge database have multiple tables, VIEW comes in handy to analyze and work with data. A VIEW is basically a virtual table created with the help of a SELECT statement. A virtual table is a table that does not have any physical existence in the physical memory but is created when called upon, though, these VIEWs are stored in a data dictionary in the MySQL server.
CREATE VIEW viewname AS SELECT col1, col2, col3 FROM tablename WHERE condition;Code language: SQL (Structured Query Language) (sql)
What do you understand by Joins?
When you want to combine two or more tables together, a JOIN clause is used. So, JOIN is an SQL clause used for combining two or more tables with one condition that there must be a related column with all the tables. There are majorly five types of JOINS:
- INNER JOIN: It returns records that are present in all the tables.
- SELF JOIN: This JOIN is used for joining a table with itself. Returns all the records of SELF-JOIN.
- LEFT OUTER JOIN: It returns all the records of the left table and records that match the right table.
- RIGHT OUTER JOIN: It returns all the records of the right table and records that match the left table.
- FULL OUTER JOIN: It returns all the records from both tables.
Also check: MySQL JOIN Interview Questions
This tutorial covered the basic questions which an entry-level MySQL Developer is expected to know. The questions covered in this tutorial are the most commonly asked questions in an entry-level interview. We hope this tutorial helped you in preparing for your interview.