https://github.com/bhartik021/sql-50-leetcode
Basic to intermediate SQL topics 50 essential SQL questions. These questions are best for 1 month of prepration time for your next interview.
https://github.com/bhartik021/sql-50-leetcode
leetcode leetcode-sql msql sql
Last synced: 11 days ago
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Basic to intermediate SQL topics 50 essential SQL questions. These questions are best for 1 month of prepration time for your next interview.
- Host: GitHub
- URL: https://github.com/bhartik021/sql-50-leetcode
- Owner: bhartik021
- License: mit
- Created: 2023-09-22T09:01:42.000Z (almost 2 years ago)
- Default Branch: main
- Last Pushed: 2023-09-27T16:27:38.000Z (almost 2 years ago)
- Last Synced: 2025-04-11T20:19:52.394Z (3 months ago)
- Topics: leetcode, leetcode-sql, msql, sql
- Homepage:
- Size: 58.6 KB
- Stars: 3
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
## SQL-50-Questions Repository
Welcome to the SQL Questions Repository! This repository contains a collection of 50 SQL questions inspired by LeetCode, aimed at helping you practice and master SQL queries. Whether you're a beginner looking to learn SQL or an experienced developer honing your skills, these questions cover a wide range of SQL topics.
## Table of Contents
1. [What is SQL?](#what-is-sql)
2. [What is MySQL?](#what-is-mysql)
3. [SQL Operations](#sql-operations)
4. [SQL Clauses](#sql-clauses)
5. [SQL Aggregation](#sql-aggregation)
6. [SQL Joins](#sql-joins)
7. [Other SQL Topics](#other-sql-topics)
8. [Learning More About SQL](#learning-more-about-sql)
9. [Conclusion](#conclusion)
## What is SQL?
SQL stands for Structured Query Language. It is a programming language designed for managing data in relational database management systems (RDBMSs).
SQL can be used to perform a variety of operations on database tables, including:
* Creating and deleting tables
* Inserting, updating, and deleting data from tables
* Querying data from tables
* Joining multiple tables together
* Grouping and aggregating data
* Creating and managing views and stored procedures
## What is MySQL?
MySQL is a popular open-source RDBMS. It is used by many companies and organizations of all sizes, including Google, Facebook, and Twitter. MySQL is known for its speed, reliability, and ease of use.
## SQL Operations
The following are some of the most common SQL operations:
* **SELECT:** Selects data from a database.
* **INSERT:** Inserts new data into a database.
* **UPDATE:** Updates existing data in a database.
* **DELETE:** Deletes data from a database.
## SQL Clauses
SQL clauses are used to specify additional conditions or requirements for a SQL statement. Some of the most common SQL clauses are:
* **WHERE:** Specifies a condition that must be met for the SQL statement to be executed.
* **ORDER BY:** Sorts the results of a SQL statement in a specific order.
* **GROUP BY:** Groups the results of a SQL statement based on a specific column or columns.
* **HAVING:** Specifies a condition that must be met for a group of rows to be included in the results of a SQL statement.
## SQL Aggregation
SQL aggregation functions allow you to perform calculations on groups of rows in a database. Some of the most common SQL aggregation functions are:
* **COUNT():** Counts the number of rows in a group.
* **SUM():** Calculates the sum of the values in a column for a group of rows.
* **AVG():** Calculates the average of the values in a column for a group of rows.
* **MIN():** Finds the smallest value in a column for a group of rows.
* **MAX():** Finds the largest value in a column for a group of rows.
## SQL Joins
SQL joins allow you to combine data from multiple tables in a database. Some of the most common SQL joins are:
* **INNER JOIN:** Combines data from two tables based on a common column or columns.
* **LEFT JOIN:** Combines data from two tables, but includes all rows from the left table, even if there are no matching rows in the right table.
* **RIGHT JOIN:** Combines data from two tables, but includes all rows from the right table, even if there are no matching rows in the left table.
* **FULL JOIN:** Combines data from two tables and includes all rows from both tables, even if there are no matching rows in the other table.
## Other SQL Topics
In addition to the topics covered above, there are many other important SQL concepts, such as:
* **Subqueries:** Subqueries are SQL statements that can be used within other SQL statements.
* **Views:** Views are virtual tables that are created based on the results of a SQL statement.
* **Transactions:** Transactions allow you to group multiple SQL statements together and ensure that they are all executed successfully or not at all.
## Learning More About SQL
There are many resources available online and in libraries to help you learn more about SQL. Here are a few suggestions:
* **W3Schools SQL Tutorial:** This tutorial provides a good overview of the basics of SQL.
* **MySQL Documentation:** The MySQL documentation is a comprehensive resource for learning about all aspects of MySQL, including SQL.
* **SQL Zoo:** SQL Zoo is an interactive website that allows you to practice writing SQL queries.
## Conclusion
SQL is a powerful language that can be used to manage data in relational database management systems. If you are interested in working with data, it is important to learn SQL.