Usage of as in mysql

Usage of AS in MySQL

Introduction
The AS keyword is used in MySQL to give an alias or temporary name in a query. It allows you to replace the original table or column name with a name that is easier to understand or use.

Usage Scenarios
The AS keyword is useful in the following scenarios:

• ##Makes the query more readable: When a table or column name is long or difficult to remember, use AS to replace it with a shorter, more user-friendly name.
• Disambiguation: When multiple tables or columns with the same name are involved in a query, AS can help distinguish them.
• Create temporary names: AS can create temporary names to store calculation results or values ​​returned from subqueries.

Using syntaxThe syntax of the AS keyword is as follows:

<code>SELECT ... AS alias_name
FROM ...
WHERE ...</code>

Among them:

• alias_name: An alias to be given to the table name or column name.
• ...: The original table name or column name to be replaced.

Example

Replace the table name "customers" with "c":

<code>SELECT * FROM customers AS c;</code>

Replace the column name "last_name" with "lname":

<code>SELECT first_name, last_name AS lname FROM employees;</code>

Create a temporary name "total_sales" to store the calculation results:

<code>SELECT SUM(sales) AS total_sales FROM orders;</code>

Note that the

AS keyword is optional. If you don't specify an alias, MySQL will automatically generate one, usually "t1", "t2", etc.
• Aliases can only be used in queries. They do not permanently change table or column names.
• The alias cannot be the same as the original name of the table or column.

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