SQL Aliases

In SQL, Aliases allow you to assign temporary names to tables or columns. They improve readability, especially in complex queries or when using JOINs and aggregate functions.

📌 Syntax

-- Column alias
SELECT column_name AS alias_name
FROM table_name;

-- Table alias
SELECT t.column_name
FROM table_name AS t;

📊 Example Tables

Users Table:

id | name
---+-------
1  | Alice
2  | Bob
3  | Charlie

Orders Table:

order_id | user_id | product
---------+---------+---------
1        | 1       | Laptop
2        | 2       | Phone
3        | 1       | Keyboard

🔍 Example 1: Column Aliases

Rename columns for better readability:

SELECT name AS user_name, id AS user_id
FROM users;

🔍 Example 2: Table Aliases with JOIN

Use table aliases to shorten query and improve clarity:

SELECT u.name AS user_name, o.product AS product_name
FROM users AS u
INNER JOIN orders AS o
ON u.id = o.user_id;

🔍 Example 3: Using Aliases in Aggregates

Assign an alias to an aggregate function result:

SELECT city, COUNT(*) AS user_count
FROM users
GROUP BY city;

⚡ Best Practices

• Use clear and meaningful alias names for better readability.
• Table aliases help when joining multiple tables to avoid ambiguity.
• Use column aliases when using functions or expressions.
• Aliases are temporary and exist only for the duration of the query.

📝 Summary

SQL Aliases allow you to rename columns or tables temporarily to make queries easier to read, understand, and maintain. They are widely used in JOINs, aggregate queries, and complex SQL statements.

🚀 Next Steps

Next, we will learn about SQL DISTINCT, which is used to retrieve unique values from a column.