using scalar function output in an update

Question

Suppose I have a 2 column table with columns (arg, value) and a user-defined function foo.

Is there a way to have an update query that goes through the table and calls foo with argument arg and sticks the results in column value for every row in the table?

Answer 1

Assuming SQL Server the syntax is

Update YourTable
SET value = dbo.foo(arg)

It is often more efficient to not use scalar UDFs for Row by Row processing however. What is the scalar UDF doing?