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Aliases are used to give a table, or a column in a table, a temporary name
Aliases are used to give a table, or a column in a table, a temporary name.
Aliases are often used to make column names more readable.
An alias only exists for the duration of that query.
An alias is created with the AS
keyword.
Alias Column Syntax
SELECT column_name AS alias_name
FROM table_name;
Alias Table Syntax
SELECT column_name(s)
FROM table_name AS alias_name;
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 creates two aliases, one for the CustomerID column and one for the CustomerName column:
SELECT CustomerID AS ID, CustomerName AS Customer
FROM Customers;
The following SQL statement creates two aliases, one for the CustomerName column and one for the ContactName column. Note: Single or double quotation marks are required if the alias name contains spaces:
SELECT CustomerName AS Customer, ContactName AS "Contact Person"
FROM Customers;
The following SQL statement creates an alias named "Address" that combine four columns (Address, PostalCode, City and Country):
SELECT CustomerName, CONCAT_WS(', ', Address, PostalCode, City, Country)
AS Address
FROM Customers;
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 use aliases to make the SQL shorter):
SELECT o.OrderID, o.OrderDate, c.CustomerName
FROM Customers AS c, Orders AS o
WHERE c.CustomerName='Around the Horn' AND c.CustomerID=o.CustomerID;
The following SQL statement is the same as above, but without aliases:
SELECT Orders.OrderID, Orders.OrderDate, Customers.CustomerName
FROM Customers, Orders
WHERE Customers.CustomerName='Around the Horn' AND Customers.CustomerID=Orders.CustomerID;
Aliases can be useful when:
When displaying the Customers
table,
make an ALIAS of the PostalCode
column,
the column should be called Pno
instead.
SELECT CustomerName, Address, PostalCode FROM Customers;