How to multiply column values in SQL Server?

Question

I would like to double the value of column C in a table. Is there a built-in function to achieve this?

Current table

       A  B  C
    X  1  2  3
    Y  4  5  6
    Z  7  8  9

After running the T-SQL or any query table values should be as below

   A  B  C
X  1  2  6
Y  4  5  12
Z  7  8  18

Answer 1

1. To select the data:

   SELECT A,B,C*2 as C
   FROM TableName
   

   Result:

   A   B   C
   1   2   6
   4   5   12
   7   8   18
   

   See result in SQL Fiddle.

2. If you want to update the table:

   UPDATE TableName
   SET C=(C * 2)