SQL: how to do an IF check for data range parameters - sql-server

Question

I am writing a stored procedure that takes in 4 parameters: confirmation_number, payment_amount, start_range, end_range.
The parameters are optional, so I am doing a check in this fashion for the confirmation_number, and the payment_amount parameters:
IF (#s_Confirmation_Number IS NOT NULL)
SET #SQL = #SQL + ' AND pd.TransactionNumber = #s_Confirmation_Number'
IF (#d_Payment_Amount IS NOT NULL)
SET #SQL = #SQL + ' AND pd.PaymentAmount = #d_Payment_Amount'
I would like to ask for help because I am not sure what is the best method to check for the date range parameters.
If someone could give me en example, or several on how this is best achieved it would be great.
Thank you in advance.
UPDATE - after receiving some great help -.
This is what I have so far, I am following scsimon recommendation, but I am not sure about the dates, I got the idea from another post I found and some playing around with it. Would you care looking at it and tell me what you all think?
Many thanks.
#s_Confirmation_Number NVARCHAR(50) = NULL
, #d_Payment_Amount DECIMAL(18, 2) = NULL
, #d_Start_Range DATE = NULL
, #d_End_Range DATE = NULL
...
....
WHERE
ph.SourceType = #s_Source_Type
AND ((pd.TransConfirmID = #s_Confirmation_Number) OR #s_Confirmation_Number IS NULL)
AND ((pd.PaymentAmount = #d_Payment_Amount) OR #d_Payment_Amount IS NULL)
AND (((NULLIF(#d_Start_Range, '') IS NULL) OR CAST(pd.CreatedDate AS DATE) >= #d_Start_Range)
AND ((NULLIF(#d_End_Range, '') IS NULL) OR CAST(pd.CreatedDate AS DATE) <= #d_End_Range))
(The parameter sourceType is a hard-coded value)

Answer 1

This is called a catch all or kitchen sink query. It is usually written as such:
create procedure myProc
(#Payment_Amount int = null
,#Confirmation_Number = null
,#start_range datetime
,#end_range datetime)
as
select ...
from ...
where
(pd.TransactionNumber = #Confirmation_Number or #Confirmation_Number is null)
and (pd.PaymentAmount = #Payment_Amount or #Payment_Amount is null)
The NULL on the two parameters gives them a default of NULL and makes them "optional". The WHERE clause evaluates this to only return rows where your user input matches the column value, or all rows when no user input was supplied (i.e. parameter IS NULL). You can use this with the date parameters as well. Just pay close attention to your parentheses. They matter a lot here because we are mixing and and or logic.
Aaron Bertrand has blogged extensively on this.

Answer 2

I do it like this
WHERE
COALESCE(#s_Confirmation_Number,pd.TransactionNumber) = pd.TransactionNumber AND
COALESCE(#d_Payment_Amount,pd.PaymentAmount) = pd.PaymentAmount
If we have a value for each of these parameters then it will check against the filter value otherwise it will always match the filter value if the parameter is null.
I've found that using COALESCE is faster and clearer than IF control statements or using OR in the WHERE clause.

Answer 3

There is another way.
But I tested and realized that a scsimon query is faster than mine.
AND (CASE
WHEN #Confirmation_Number is not null
THEN (CASE
WHEN pd.TransactionNumber = #Confirmation_Number
THEN 1
ELSE 0
END)
ELSE 1
END = 1)