Aliases

An alias gives a column or table a temporary name for the duration of a query. It is written with the AS keyword (optional).

Column aliases

sql

### SELECT CustomerName AS Client

### FROM Customers;

The result column is now labeled "Client" instead of "CustomerName".

Alias for calculated columns

sql

### SELECT ProductName, Price * 2 AS DoublePrice

### FROM Products;

The Price * 2 column gets the readable name "DoublePrice".

Concatenate columns

sql
SELECT CustomerName, Address + ', ' + City AS Address

### FROM Customers;

(Note: CONCAT() is used in MySQL instead of +.)

Table aliases

sql

### SELECT o.OrderID, c.CustomerName

### FROM Orders AS o
INNER JOIN Customers AS c ON o.CustomerID = c.CustomerID;

Now you can write o.OrderID instead of Orders.OrderID.

Spaces in aliases

If an alias has a space, wrap it in quotes:

sql

### SELECT CustomerName AS "Full Name"

### FROM Customers;

TL;DR

• Aliases give temporary names to columns or tables.
• Written as AS name (AS is optional).
• Table aliases make long queries shorter.
• Use quotes for aliases with spaces.