Database Admin

Database Admin Interview Questions and Answers for Freshers

Updated 23 Oct 2024

Q1. What is the Postgres Architecture, explain it in depth.

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Postgres Architecture is a client-server model with a multi-process approach.

Postgres uses a multi-process approach with a master process and worker processes.
The master process manages shared memory and worker processes handle client connections.
Postgres also has a background process for maintenance tasks and a WAL writer for data durability.
Postgres supports ACID transactions and has a query planner for optimizing queries.
Postgres also has a storage manager for managing dis...read more

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A database is a structured collection of data. SQL is a language used to manage and manipulate databases.

A database is a software system that stores and organizes data.
It allows users to create, read, update, and delete data.
SQL (Structured Query Language) is a programming language used to communicate with and manage databases.
There are different types of databases such as relational databases, object-oriented databases, and NoSQL databases.
Relational databases use tables to ...read more

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Use SQL queries to segregate alphabet and numbers in a table

Use the SQL function REGEXP to filter out alphabets and numbers
For example, to select only alphabets: SELECT column_name FROM table_name WHERE column_name REGEXP '^[a-zA-Z]'
For numbers: SELECT column_name FROM table_name WHERE column_name REGEXP '^[0-9]'

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A view is a virtual table based on the result-set of an SQL statement. A materialized view is a physical copy of a view.

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Ans.

Using a case statement in a query to handle different conditions

Use CASE statement to handle different conditions in a query
CASE can be used for conditional logic within SELECT, WHERE, ORDER BY clauses
Example: SELECT column1, CASE WHEN condition1 THEN 'Result1' ELSE 'Result2' END AS new_column FROM table_name

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SQL command of which database?

Specify the name of the database you want the SQL command for
Provide the specific query you want to execute
Ensure that the syntax is correct and the query is optimized
Examples: SELECT * FROM table_name; INSERT INTO table_name (column1, column2) VALUES (value1, value2);

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A standalone database is a database that is independent and does not require connection to a network or other databases.

Standalone databases are typically used for small-scale applications or for testing purposes.
They do not rely on a network connection to function.
Examples of standalone databases include SQLite and Microsoft Access.

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Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity.

Normalization involves breaking down a table into smaller tables and defining relationships between them.
There are different levels of normalization, known as normal forms, with each level having specific rules to follow.
The most commonly used normal forms are first normal form (1NF), second normal form (2NF), and third normal form (3NF).
Normalization helps to prevent...read more