Comma before 'if'

[dreamwarrior]

If a sentence begins with the 'if' clause, a comma is usually used after that clause. Are there any instances where comma is used before the 'if' clause as in the following:

Select an option from the drop-down list, if you have configured the database details.

Select an option from the drop-down list if you have configured the database details.

Which is correct?

Are there any difference in usage between UK and US English for this?

 

[Barb_D]

I would go without the comma.

(I also hope you tell the person what do to if you have NOT yet configured the details.)