SQL · Chapter 14 of 42
SQL Aliases
Aliases give a temporary alternative name to a column or table using AS.
Column aliases rename output; table aliases shorten JOIN queries.
Column aliases
`SELECT price * 1.18 AS gross FROM products;`
Table aliases
`SELECT u.name FROM users AS u;` — makes joins compact and readable.
Example 1 (sql)
SELECT first_name AS fname, last_name AS lname FROM users;Output
fname | lname
Ana | Rao
Ben | LeeRename columns in output.
Example 2 (sql)
SELECT u.name, o.total
FROM users u
JOIN orders o ON o.user_id = u.id;Output
user + total per orderTable aliases keep JOINs readable.
Key points
- `AS name` renames columns or tables.
- AS is optional — `users u` also works.
- Aliases exist only for the query lifetime.
- Cannot reference an alias in the same WHERE clause (dialect-dependent).
💡 Note: Alias table names to short letters (`u`, `o`, `p`) in complex joins — SQL readability jumps.