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SQL Aliases (AS) 🏷️

Prerequisites: SELECT Statement

Mentor's Note: Aliases are like "Nicknames". They don't change the actual name in the database, but they make your results and your code much easier to read. 💡

🌟 The Scenario: The Nickname 📛

  • Actual Name: "Christopher Columbus"
  • Alias: "Chris"
  • Technical Column: p_id_001_sales_net
  • Alias: Price ✅

💻 1. Column Aliases 📊

Used to make column headers more descriptive or readable.

-- Scenario: Calculating total price with tax
SELECT 
    product_name, 
    price * 1.18 AS "Price_With_Tax" -- 🏷️ Readable Alias
FROM products;

Rules: - The AS keyword is optional but recommended. - Use Double Quotes " " if the alias has spaces.

💻 2. Table Aliases 🏢

Used to shorten table names, especially when joining multiple tables together.

-- Scenario: Fetching employee and department names
SELECT E.name, D.dept_name
FROM employees AS E -- 🏷️ E is easier to type than employees
JOIN departments AS D ON E.dept_id = D.id;

🎨 Visual Logic: The Map

Technical Database Query View (The Alias)
emp_first_name First_Name
dept_loc_zip Zip_Code
salary + bonus Total_Pay

💡 Pro Tip

"In Joins, always use Table Aliases (like E for Employees). It prevents 'Ambiguous Column' errors if both tables have a column with the same name (like created_at)."

📈 Learning Path