SQL queries are fundamental for interacting with relational databases. This guide covers basic syntax, common commands, and practical examples to help you master query writing.

Basic Concepts 🔍

  • SELECT: Retrieves data from one or more tables
  • FROM: Specifies the table to query
  • WHERE: Filters records based on conditions
  • JOIN: Combines rows from multiple tables
  • ORDER BY: Sorts the result set

Example Queries 📝

-- Simple SELECT statement  
SELECT * FROM employees;  

-- Filtering with WHERE  
SELECT name, salary FROM employees WHERE department = 'Sales';  

-- Joining two tables  
SELECT orders.order_id, customers.name  
FROM orders  
JOIN customers ON orders.customer_id = customers.id;

Best Practices ✅

  1. Use LIMIT to restrict results
  2. Avoid SELECT * for performance optimization
  3. Format queries with proper indentation
  4. Leverage this tutorial for foundational knowledge
sql_query

For advanced topics like subqueries or aggregate functions, visit our SQL Advanced Guide. 🚀