> ## Documentation Index > Fetch the complete documentation index at: https://villagesql.com/docs/llms.txt > Use this file to discover all available pages before exploring further. # MySQL column aliases > How to rename a column in a MySQL result with AS, which quoting style to use, why a computed column always wants an alias, and what AS does not change. All examples on this page work on VillageSQL. Install Now → A result set takes its column headings from whatever you put in the select list. For a plain column that heading is the column name, which is usually fine. For a calculation it is the expression you typed, which is not. An alias replaces that heading with a name you choose. Open the client with `mysql -u root -p sakila` before you start. ## How an alias works ```sql theme={null} SELECT COLUMN_OR_EXPRESSION AS ALIAS_NAME FROM TABLE_NAME; ``` Replace `COLUMN_OR_EXPRESSION` with the column or calculation you want, `ALIAS_NAME` with the heading you want it to have, and `TABLE_NAME` with the table. The alias applies to the result only. Nothing about the table changes, and the next query knows nothing about it. ## Examples ### 1) Rename a column ```sql theme={null} SELECT title AS film_title FROM film; ``` ```text theme={null} +-----------------------------+ | film_title | +-----------------------------+ | ACADEMY DINOSAUR | | ACE GOLDFINGER | | ADAPTATION HOLES | | AFFAIR PREJUDICE | | AFRICAN EGG | ... +-----------------------------+ 1000 rows in set (0.00 sec) ``` The heading reads `film_title`. The values are untouched. ### 2) Name a calculation This is where an alias earns its place. Without one the heading is the arithmetic. ```sql theme={null} SELECT title, rental_rate * 1.1 AS price_with_tax FROM film; ``` ```text theme={null} +-----------------------------+----------------+ | title | price_with_tax | +-----------------------------+----------------+ | ACADEMY DINOSAUR | 1.089 | | ACE GOLDFINGER | 5.489 | | ADAPTATION HOLES | 3.289 | | AFFAIR PREJUDICE | 3.289 | | AFRICAN EGG | 3.289 | ... +-----------------------------+----------------+ 1000 rows in set (0.00 sec) ``` Application code reads results by column name, so an unnamed expression leaves that code depending on the exact text of your arithmetic. ### 3) An alias containing a space An alias made of letters, digits and underscores needs no quoting. Anything else does, including a space or a word MySQL has reserved for its own use, such as `order` or `select`. Backticks are the quoting style to reach for. ```sql theme={null} SELECT title AS `Film Title` FROM film; ``` ```text theme={null} +-----------------------------+ | Film Title | +-----------------------------+ | ACADEMY DINOSAUR | | ACE GOLDFINGER | | ADAPTATION HOLES | ... +-----------------------------+ 1000 rows in set (0.00 sec) ``` Single quotes produce the same heading: ```sql theme={null} SELECT title AS 'Film Title' FROM film; ``` ```text theme={null} +-----------------------------+ | Film Title | +-----------------------------+ | ACADEMY DINOSAUR | | ACE GOLDFINGER | | ADAPTATION HOLES | ... +-----------------------------+ 1000 rows in set (0.00 sec) ``` They are not equivalent everywhere, though. Backticks mark a name, while single quotes mark a string, and a later clause that refers back to the alias can tell the difference. The next lesson shows that going wrong. Use backticks and the question never comes up. Leave the quotes off entirely and the server stops at the space: ```sql theme={null} SELECT title AS Film Title FROM film; ``` ```text theme={null} ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'Title FROM film' at line 1 ``` `ERROR 1064` is the general syntax error. The quoted fragment at the end of the message is where the server gave up, which is normally a word or two after the real mistake. ## AS is optional, and leaving it out hides a typo A bare name after a column means the same as `AS`. That is also how a forgotten comma disguises itself. ```sql theme={null} SELECT title release_year FROM film; ``` ```text theme={null} +-----------------------------+ | release_year | +-----------------------------+ | ACADEMY DINOSAUR | | ACE GOLDFINGER | | ADAPTATION HOLES | ... +-----------------------------+ 1000 rows in set (0.00 sec) ``` That was meant to be 2 columns. The missing comma turned `release_year` into an alias for `title`, so the result has 1 column, headed `release_year`, holding film titles. The server raised nothing, because the statement is valid. Writing `AS` on every alias does not make the server reject this, because neither column here has one. It does make the mistake visible when you read the query back: a bare name after a column, with no `AS` in front of it, is a missing comma. ## Summary * Use `AS` to give a result column a name of your own. * Always alias a computed column, because its default heading is the expression. * Quote an alias with backticks when it contains a space or a reserved word. * Write `AS` on every alias, so a bare name reads as a missing comma. ## See also * [SELECT](/docs/tutorial/select) — the statement an alias attaches to * [ORDER BY](/docs/tutorial/order-by) — sorting a result, where the quoting style starts to matter * [MySQL string functions](/docs/guides/string-functions) — expressions that need a name