SQL aliases are used to temporarily rename a table or a column heading.
SQL aliases are used to give a database table, or a column in a table, a temporary name.
Basically aliases are created to make column names more readable.
In this tutorial we will use the well-known Northwind sample database.
Below is a selection from the "Customers" table:
CustomerID | CustomerName | ContactName | Address | City | PostalCode | Country |
---|---|---|---|---|---|---|
2 | Ana Trujillo Emparedados y helados | Ana Trujillo | Avda. de la Constitución 2222 | México D.F. | 05021 | Mexico |
3 | Antonio Moreno Taquería | Antonio Moreno | Mataderos 2312 | México D.F. | 05023 | Mexico |
4 | Around the Horn | Thomas Hardy | 120 Hanover Sq. | London | WA1 1DP | UK |
And a selection from the "Orders" table:
OrderID | CustomerID | EmployeeID | OrderDate | ShipperID |
---|---|---|---|---|
10354 | 58 | 8 | 1996-11-14 | 3 |
10355 | 4 | 6 | 1996-11-15 | 1 |
10356 | 86 | 6 | 1996-11-18 | 2 |
The following SQL statement specifies two aliases, one for the CustomerName column and one for the ContactName column. Tip: It requires double quotation marks or square brackets if the column name contains spaces:
In the following SQL statement we combine four columns (Address, City, PostalCode, and Country) and create an alias named "Address":
Note: To get the SQL statement above to work in MySQL use the following:
The following SQL statement selects all the orders from the customer with CustomerID=4 (Around the Horn). We use the "Customers" and "Orders" tables, and give them the table aliases of "c" and "o" respectively (Here we have used aliases to make the SQL shorter):
The same SQL statement without aliases:
Aliases can be useful when: