MySQL Aliases: Use AS to Rename Columns

An alias is a temporary name that exists only for one query. It makes results readable and queries shorter.

query.sql

SQL

CREATE TABLE products (
    id INT AUTO_INCREMENT PRIMARY KEY,
    name VARCHAR(100) NOT NULL,
    category VARCHAR(50) NOT NULL,
    price DECIMAL(8,2) NOT NULL,
    stock INT NOT NULL DEFAULT 0,
    added_on DATE NOT NULL
);

INSERT INTO products (name, category, price, stock, added_on) VALUES
    ('Notebook',      'stationery',  80.00, 120, '2026-01-10'),
    ('Gel Pen',       'stationery',  15.50, 300, '2026-01-12'),
    ('Backpack',      'bags',       999.00,  25, '2026-02-01'),
    ('Marker Set',    'stationery', 145.00,   0, '2026-02-15'),
    ('Desk Lamp',     'home',       650.00,  40, '2026-03-03'),
    ('Water Bottle',  'home',       220.00,  75, '2026-03-20'),
    ('Laptop Sleeve', 'bags',       450.00,  18, '2026-04-02'),
    ('Sticky Notes',  'stationery',  35.00, 210, '2026-04-18');

Column aliases

query.sql

SQL

SELECT name AS product, price * stock AS stock_value
FROM products
WHERE stock > 0
ORDER BY stock_value DESC
LIMIT 3;

Output

OUTPUT

+--------------+-------------+
| product      | stock_value |
+--------------+-------------+
| Desk Lamp    |    26000.00 |
| Backpack     |    24975.00 |
| Water Bottle |    16500.00 |
+--------------+-------------+
3 rows in set

Without AS stock_value, the column header would be the whole expression price * stock. The alias is also what your application code reads ($row['stock_value']).

AS is optional (price * stock stock_value works), but always write it. Without it, a forgotten comma turns into an accidental alias. This query is missing a comma:

query.sql

SQL

SELECT name price FROM products LIMIT 2;

Output

OUTPUT

+----------+
| price    |
+----------+
| Notebook |
| Gel Pen  |
+----------+
2 rows in set

MySQL did not complain. It read price as an alias for name, so the result has a column called price holding the product names. AS makes such a mistake easy to spot.

Aliases with spaces

Wrap an alias that contains spaces or special characters in backticks:

query.sql

SQL

SELECT name AS `Product Name`, price AS `Price (INR)` FROM products LIMIT 2;

Output

OUTPUT

+--------------+-------------+
| Product Name | Price (INR) |
+--------------+-------------+
| Notebook     |       80.00 |
| Gel Pen      |       15.50 |
+--------------+-------------+
2 rows in set

Aliases with spaces are for reports. In application code use snake_case names.

Table aliases

A table alias shortens the table name, which matters in joins:

query.sql

SQL

1
2
3

SELECT p.name, p.price
FROM products AS p
WHERE p.category = 'home';

Output

OUTPUT

+--------------+--------+
| name         | price  |
+--------------+--------+
| Desk Lamp    | 650.00 |
| Water Bottle | 220.00 |
+--------------+--------+
2 rows in set

Here p stands for products. It becomes necessary in a self-join, where the same table appears twice (Self Joins), and when you join two tables that have columns with the same name.

Where you can use an alias

Clause	Column alias allowed?	Why
`ORDER BY`	Yes	It runs after `SELECT`
`GROUP BY`	Yes in MySQL (not standard)	MySQL extension
`HAVING`	Yes in MySQL (not standard)	MySQL extension
`WHERE`	No	It runs before `SELECT`
Another select expression in the same `SELECT`	No	Not available yet

query.sql

SQL

SELECT price * stock AS stock_value FROM products WHERE stock_value > 5000;

Output

OUTPUT

ERROR 1054 (42S22): Unknown column 'stock_value' in 'where clause'

WHERE cannot see stock_value. Repeat the expression, or wrap the query in a derived table:

query.sql

SQL

SELECT name, stock_value
FROM (SELECT name, price * stock AS stock_value FROM products) AS t
WHERE stock_value > 5000
ORDER BY stock_value DESC;

Output

OUTPUT

+---------------+-------------+
| name          | stock_value |
+---------------+-------------+
| Desk Lamp     |    26000.00 |
| Backpack      |    24975.00 |
| Water Bottle  |    16500.00 |
| Notebook      |     9600.00 |
| Laptop Sleeve |     8100.00 |
| Sticky Notes  |     7350.00 |
+---------------+-------------+
6 rows in set

warning

Subquery in FROM needs an alias

In MySQL every derived table must have an alias. FROM (SELECT ...) without AS t gives error 1248, “Every derived table must have its own alias”.