Technical interview questions and answers are essential when preparing for a MySQL Interview because companies want to evaluate your understanding of database queries, joins, functions, table design, indexing, and optimization techniques. MySQL is widely used in web applications, making it one of the most important skills for developers, database engineers, and backend programmers. Companies like TCS, Wipro, Infosys, Cognizant, and Accenture frequently include MySQL questions in technical rounds and placement tests. This guide provides the most asked MySQL interview questions with explanations to help freshers and job seekers strengthen their SQL fundamentals. Preparing these questions will help you perform confidently in SQL coding tests, backend interviews, and campus placements.
Database developers can broaden their expertise through DBMS theory and MS SQL Server implementation
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11. What does i-am-a-dummy flag to do when starting MySQL?
Makes the MySQL engine refuse UPDATE and DELETE commands where the WHERE clause is not present.
12. On executing the DELETE statement I keep getting the error about foreign key constraint failing. What do I do?
What it means is that so of the data that youre trying to delete is still alive in another table. Like if you have a table for universities and a table for students, which contains the ID of the university they go to, running a delete on a university table will fail if the students table still contains people enrolled at that university. Proper way to do it would be to delete the offending data first, and then delete the university in question. Quick way would involve running SET foreign_key_ch
13. When would you use ORDER BY in DELETE statement?
When youre not deleting by row ID. Such as in DELETE FROM techpreparation_com_questions ORDER BY timestamp LIMIT 1. This will delete the most recently posted question in the table techpreparation_com_questions.
14. How can you see all indexes defined for a table?
SHOW INDEX FROM techpreparation_questions;
15. How would you change a column from VARCHAR(10) to VARCHAR(50)?
ALTER TABLE techpreparation_questions CHANGE techpreparation_content techpreparation_CONTENT VARCHAR(50).
16. How would you delete a column?
ALTER TABLE techpreparation_answers DROP answer_user_id.
17. How would you change a table to InnoDB?
ALTER TABLE techpreparation_questions ENGINE innodb;
18. When you create a table, and then run SHOW CREATE TABLE on it, you occasionally get different results than what you typed in. What does MySQL modify in your newly created tables?
1. VARCHARs with length less than 4 become CHARs
2. CHARs with length more than 3 become VARCHARs.
3. NOT NULL gets added to the columns declared as PRIMARY KEYs
4. Default values such as NULL are specified for each column
19. How do I find out all databases starting with ‘tech to which I have access to?