database interview questions:
What is a database?
A database is a collection of data that is organized and stored in a structured way. It is used to manage large amounts of information and to provide fast and efficient access to that information.
What is SQL and what is it used for?
SQL (Structured Query Language) is a programming language that is used to manage and manipulate data in relational databases. It is used to create, modify, and query databases and tables, and is widely used in web development and data analysis.
What is a primary key and why is it important?
A primary key is a unique identifier for a row in a database table. It is used to ensure that each row can be uniquely identified and accessed, and is important for maintaining data integrity and ensuring that data is organized and easy to manage.
What is normalization and why is it important?
Normalization is the process of organizing data in a database in a way that reduces redundancy and dependency, and ensures that data is stored in a consistent and efficient manner. It is important because it helps to reduce data duplication, improve data consistency, and make databases easier to manage and maintain.
What is indexing and why is it important?
Indexing is the process of creating a data structure that improves the speed and efficiency of database queries. It is important because it helps to speed up queries and improve the performance of database applications.
What is a foreign key and how is it used?
A foreign key is a field in a database table that refers to the primary key of another table. It is used to establish a relationship between the two tables, and is used to enforce referential integrity and ensure that data is consistent across the database.
What is a transaction and why is it important?
A transaction is a set of database operations that are treated as a single, atomic unit of work. It is important because it helps to ensure that database operations are executed in a consistent and reliable way, and that data is kept in a consistent state.
What is ACID in the context of databases?
ACID (Atomicity, Consistency, Isolation, Durability) is a set of properties that describe the reliability and consistency of database transactions. Atomicity ensures that transactions are treated as a single unit of work, consistency ensures that data is always valid and consistent, isolation ensures that transactions do not interfere with each other, and durability ensures that data is permanently stored and can be recovered in the event of a failure.
What is a stored procedure and how is it used?
A stored procedure is a precompiled set of SQL statements that is stored in a database and can be executed on demand. It is used to perform complex database operations, and can be used to improve performance and reduce network traffic.
What is NoSQL and how is it different from SQL databases?
NoSQL (Not Only SQL) is a type of database that is designed to handle large volumes of unstructured or semi-structured data. It is different from SQL databases in that it does not use a fixed schema, and allows for more flexible and scalable data storage and retrieval.
