if then else in stored procedure

[Garima12]

There is a piece of code from stored procedure.

BEGIN

SET NOCOUNT ON;
	SELECT 
	  pi.*
FROM rates pi
WHERE
(pi.pid = @pid or @pid is NULL) 	
AND
(pi.scode = @scode or @scode is NULL)

END

I want to put a condition in this:
If scode = 'p' then
where condition must be like this:
WHERE
(pi.pid = @pid or @pid is NULL)
AND
((pi.scode = @scode and pi.scode ='p' ) or @scode is NULL)

Please tell me how to modify the code?
thks

[ck9663]

There is a piece of code from stored procedure.

BEGIN

SET NOCOUNT ON;
	SELECT 
	  pi.*
FROM rates pi
WHERE
(pi.pid = @pid or @pid is NULL) 	
AND
(pi.scode = @scode or @scode is NULL)

END

I want to put a condition in this:
If scode = 'p' then
where condition must be like this:
WHERE
(pi.pid = @pid or @pid is NULL)
AND
((pi.scode = @scode and pi.scode ='p' ) or @scode is NULL)

Please tell me how to modify the code?
thks

On this part:

If scode = 'p'

Is scode a variable or a column?

-- CK