With SQL, an alias name can be given to a table or to a column.
You can give a table or a column another name by using an alias. This can be a good thing to do if you have very long or complex table names or column names.
An alias name could be anything, but usually it is short.
SQL Alias Syntax for Tables
SQL Alias Syntax for Columns
|SELECT column_name AS alias_name|
Assume we have a table called "Persons" and another table called "Product_Orders". We will give the table aliases of "p" and "po" respectively.
Now we want to list all the orders that "Ola Hansen" is responsible for.
We use the following SELECT statement:
|SELECT po.OrderID, p.LastName, p.FirstName|
FROM Persons AS p,
Product_Orders AS po
WHERE p.LastName='Hansen' AND p.FirstName='Ola'
The same SELECT statement without aliases:
|SELECT Product_Orders.OrderID, Persons.LastName, Persons.FirstName|
WHERE Persons.LastName='Hansen' AND Persons.FirstName='Ola'
As you'll see from the two SELECT statements above; aliases can make queries easier to both write and to read.