MySQL Aliases

An alias is a temporary name for a column or a table. It exists only while the query runs. You create it with AS.

Column alias

SELECT name AS student_name, marks AS score FROM students LIMIT 2;

Result

student_name	score
Robin	85
Maria	92

The headers of the result are now the alias names. This is useful for calculated columns.

SELECT name, marks + 5 AS marks_with_bonus FROM students LIMIT 2;

Result

name	marks_with_bonus
Robin	90
Maria	97

If the alias has a space, put it in backticks: AS `total marks`.

A table alias is a short name for a table. It makes long queries shorter, and it is needed when you join a table with itself.

SELECT s.name, c.course_name
FROM students AS s
JOIN courses AS c ON s.course_id = c.id
ORDER BY s.id
LIMIT 2;

Result

name	course_name
Robin	Python
Maria	Java

You can leave out the word AS: FROM students s works the same. Learn JOINs in a later chapter.

Note: You cannot use a column alias in the WHERE clause, because WHERE runs before the alias is created. You can use it in ORDER BY and GROUP BY.

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