? MySQL Aliases

? Quick Overview

In MySQL, an alias is a temporary name assigned to a table or column for the duration of a query. Aliases improve readability and simplify queries — especially joins or queries with long identifiers.

? Key Concepts

Column Alias: Rename columns in the result set (optional AS keyword).
Table Alias: Temporary table name, commonly used in joins and subqueries.
Scope: Aliases exist only for the duration of the query execution — they don't change schema.
Readability: Use clear, descriptive aliases to make complex SQL easier to follow.

? Syntax / Theory

? View Code Example

-- Syntax for Column Alias (rename a column in SELECT)
SELECT column_name AS alias_name
FROM table_name;
-- Syntax for Table Alias (give a temporary name to a table)
SELECT column_name
FROM table_name AS alias_name;

? Code Example(s)

? View Code Example

-- Using column alias to rename 'student_name' as 'name' and 'student_id' as 'id'
SELECT student_name AS name, student_id AS id
FROM students;
-- Using table alias 's' for the 'students' table and filtering by age
SELECT s.student_name, s.student_id
FROM students AS s
WHERE s.student_age > 18;

? Live Output / Explanation

Explanation

Column Alias: When you use student_name AS name, the result set column will be labeled name.
Table Alias: students AS s lets you reference the table as s (handy for joins or long table names).
AS is optional: SELECT student_name name also works, but using AS increases clarity.

✅ Tips & Best Practices

Prefer descriptive aliases (e.g., customer_total instead of ct) for maintainability.
Use table aliases to disambiguate columns when joining multiple tables with similar column names.
Avoid spaces in alias names; use underscores or camelCase if needed.

? Try It Yourself

Write a query to select product_name and price from products, aliasing them to name and cost.
Join students (alias s) with courses (alias c) and select student name and course title.
Show first name and last name of employees as first and last using column aliases.