SQL AS

SQL SQL MOC

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The AS command assigns an alias to a table or field to temporarily rename it for the query. These can help make long SQL statements more readable or descriptive.

SELECT field AS aliasname FROM tablename;

Example

customers table

customerId	firstName	lastName	address	city	country
1	Ursa	Vasquez	P.O. Box 878, 8416 Nullam St.	Worcester	United States
2	Quyn	Meyer	P.O. Box 670, 7155 Tincidunt St.	Price	Canada
3	Orli	Klein	4981 Gravida St.	Barrow-in-Furness	United Kingdom
4	Tallulah	Hines	6279 Pellentesque Street	Omaha	United States
5	Joel	Ross	P.O. Box 842, 4634 Egestas Avenue	Clovenfords	United Kingdom
6	Charlotte	Ramos	794-1654 A Rd.	Akron	United States
7	Dennis	Avery	P.O. Box 506, 4804 Molestie Avenue	Matlock	United Kingdom
8	Igor	Malone	6627 Porttitor Rd.	Irvine	United Kingdom
9	Connor	Witt	5979 Vel St.	Tain	United Kingdom
10	Karen	Marquez	Ap 524-1173 Metus. Road	Annapolis Royal	Canada

SELECT customerId, CONCAT_WS(' ', firstName, lastName) AS fullName FROM customers;

customerId	fullName
1	Ursa Vasquez
2	Quyn Meyer
3	Orli Klein
4	Tallulah Hines
5	Joel Ross
6	Charlotte Ramos
7	Dennis Avery
8	Igor Malone
9	Connor Witt
10	Karen Marquez

Table Names

Aliases can shorten queries as well.

SELECT orders.orderId, customers.firstName, customers.lastName, orders.currency, orders.total
FROM orders, customers
WHERE orders.customerId = customers.customerId;

With AS, this query becomes the following.

SELECT o.orderId, c.firstName, c.lastName, o.currency, o.total
FROM orders AS o, customers AS c
WHERE o.customerId = c.customerId;