Database Developer Interview Questions and Answers for Freshers

Interview questions for Database Developer

• Waterfall model is a linear approach to software development

• Cursor is a database object used to manipulate data row by row

• Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity, while denormalization is the process of intentionally introducing redundancy to improve performance

• SDLC Lifecycle is a process followed by a development team to create a software product

• SQL is used to mana...read more

Optimize select statements by using indexes, avoiding unnecessary joins, and limiting the number of columns selected.

• Use indexes to speed up queries

• Avoid unnecessary joins and subqueries

• Limit the number of columns selected

• Use WHERE clauses to filter results

• Use GROUP BY and ORDER BY clauses wisely

• Consider using stored procedures or views

• Regularly analyze and optimize the database

Indexing is a technique to improve database performance by reducing the time taken to retrieve data.

• Indexes are created on one or more columns of a table.

• Types of indexes include clustered, non-clustered, unique, and full-text indexes.

• Clustered indexes determine the physical order of data in a table.

• Non-clustered indexes are separate structures that contain a copy of the indexed columns and a pointer to the actual data.

• Unique indexes ensure that each value in the indexed colu...read more

Joins are used to combine data from two or more tables based on a related column. A view is a virtual table created from a query.

• Joins are used to retrieve data from multiple tables based on a related column

• There are different types of joins such as inner join, left join, right join, and full outer join

• Views are virtual tables created from a query that can be used to simplify complex queries or restrict access to sensitive data

• Views do not store data themselves, but rather pr...read more

SQL is a programming language used to manage and manipulate relational databases.

• SQL stands for Structured Query Language

• It is used to create, modify, and query databases

• It is used in various industries such as finance, healthcare, and e-commerce

• Examples of SQL-based databases include MySQL, Oracle, and Microsoft SQL Server

Drop command removes the entire table while delete command removes specific rows.

• Drop command is a DDL (Data Definition Language) command while delete command is a DML (Data Manipulation Language) command.

• Drop command cannot be rolled back while delete command can be rolled back using transaction.

• Drop command is faster than delete command as it removes the entire table at once.

• Example: DROP TABLE table_name; DELETE FROM table_name WHERE condition;

Query to find the total sales amount for each product category

• Use GROUP BY clause to group the sales by product category

• Use SUM function to calculate the total sales amount

• Join the sales table with the product table to get the product category

Performance tuning techniques for database developers

• Optimizing SQL queries by using indexes and proper query structure

• Regularly monitoring and analyzing database performance metrics

• Using caching mechanisms to reduce database load

• Partitioning large tables to improve query performance

• Optimizing database schema design for efficient data retrieval