SQL Aliases

SQL Aliases

SQL 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

SQL 
SELECT column_name AS alias_name
FROM table_name;

Alias Table Syntax

SQL 
SELECT column_name(s)
FROM table_name AS alias_name;

Alias for Columns Examples

The following SQL statement creates two aliases, one for the CustomerID column and one for the CustomerName column:

SQL 
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: It requires double quotation marks or square brackets if the alias name contains spaces:

SQL 
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):

SQL 
SELECT CustomerName, Address + ', ' + PostalCode + ' ' + City + ', ' + Country AS Address
FROM Customers;

Note: To get the SQL statement above to work in MySQL use the following:

SQL 
SELECT CustomerName, CONCAT(Address,', ',PostalCode,', ',City,', ',Country) AS Address
FROM Customers;

Alias for Tables Example

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):

SQL 
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:

SQL 
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:

  • There are more than one table involved in a query
  • Functions are used in the query
  • Column names are big or not very readable
  • Two or more columns are combined together