What does as mean in mysql

AS in MySQL is used to create table or column aliases to simplify the reference of tables or columns in queries: Table alias: When using multiple tables in a query, specify a table alias to reference columns in the table more convenient. Column alias: Specify a column alias to use a different name or alias in query results.

The meaning of AS in MySQL

AS is a reserved keyword in MySQL and is used to create table aliases or column alias.

Table alias

When using multiple tables in a query, you can use AS to specify aliases for the tables to make it more convenient to reference columns in the tables. For example:

SELECT * FROM users AS u, orders AS o
WHERE u.id = o.user_id;

In this query, the tables users and orders are assigned the aliases u and o. This allows you to use aliases to reference columns in the table, such as u.id and o.user_id.

Column alias

You can also use AS to specify an alias for a column so that different names or aliases can be used in query results. For example:

SELECT name AS full_name FROM users;

In this query, the name column is assigned the alias full_name. In the query results, the name column will appear as full_name.

Usage

The syntax for creating an alias using AS is as follows:

<code> AS </code>

Among them:

• ## is the alias to be created.
• is the original name of the table or column for which you want to create an alias.

Advantages

Using aliases can make queries easier to understand and maintain, especially when multiple tables or columns are used in a query. Aliases can help eliminate ambiguity and make query results more intuitive.

The above is the detailed content of What does as mean in mysql. For more information, please follow other related articles on the PHP Chinese website!