MySQL questions for interview preparation

Q5: What is MySQL Workbench?

Ans: MySQL Workbench is a unified visual database design or graphical user interface (GUI) tool for MySQL databases. Oracle created and maintained it, and it offers SQL creation, data migration, and complete administrative tools for server configuration, user management, backup, and so on. This Server Administration may construct new physical data models, E-R diagrams, and SQL development. It is compatible with all major operating systems. MySQL Server versions 5.6 and above provide support for it. It is mainly available in three editions, which are given below:

  • Community Edition (Open Source, GPL)
  • Standard Edition (Commercial)
  • Enterprise Edition (Commercial)

Q6: How does indexing works in MySQL?

Ans: Indexing is a method of converting an unordered list into an ordered list. It aids in increasing the query's performance when searching tables in MySQL. The operation of MySQL indexing is similar to that of a book index.

Assume we have a book and wish to learn about, say, searching. Without indexing, it is necessary to go through each page one by one until the desired topic is located. On the other hand, an index contains a collection of keywords that may be used to discover the topic addressed on pages. Then we may go right to those pages without having to browse through all of them.

Q7: What are CHAR and VARCHAR in MySQL?

Ans: They both define a string. The primary distinction is that CHAR is a fixed-length value, whereas VARCHAR is variable length. For instance, if CHAR(5) is specified, it requires precisely five characters. If VARCHAR(5) is specified, it can only accept up to five characters. Because it may have dynamic memory allocations, VARCHAR is claimed to be more efficient in memory use.

Q8: Explain the difference between DELETE and TRUNCATE.

Ans:  To delete records from a database table, the DELETE and TRUNCATE commands are used. However, there are several important distinctions between these instructions. The effect of these commands may be correctly displayed if the table has the AUTO_INCREMENT PRIMARY KEY column.

Two differences between these commands are mentioned below.

  • The DELETE command is used to remove a single, many, or all records from a table. TRUNCATE is used to remove all records from a table or to make the table empty.
  • When the DELETE command is used to delete all the records from a table, the table is not re-initialized. As a result, when the user enters a record, the AUTO_INCREMENT field does not count from one.

However, when all the records in a table are removed using the TRUNCATE command, the table is re-initialized, and a new record starts from one for the AUTO_INCREMENT column.

Q9: Can a query be written in any case in MySQL?

Ans: This MySQL interview question frequently perplexes persons who are just starting with MySQL. Even though most queries are written in capital or small characters, there is no case sensitivity in MySQL queries. Both create table name and CREATE TABLE table name, for example, work perfectly. However, if necessary, the term BINARY can be used to make the query case sensitive.