Question

So if my store procedure is called with a null item I want to make it ” (otherwise it won’t work with my result list)
How does one do this?

I would like my code to spit out the population for one country if the country input was US,null,null, or I want it more specific population if US,New York, New York City is put in. So population of New York City.

Create procedure [dbo].[GetPopulation]

        @CountryCode varchar(3),
    @State varchar(80)=null,
    @City varchar(80)=null
as
if @State is Null 
    @State = ''
if @City is Null 
    @City = ''

select Population
FROM Countries
Where CountryCode = @CountryCode AND State = @State AND City=@City

Answer 1

If I am right you want to ignore where clause’s when parameter is null

select Population
FROM Countries
Where (CountryCode = @CountryCode OR @CountryCode IS NULL)
 AND (State = @State OR @State IS NULL)
 AND (City=@City OR @City IS NULL)

In case your problem is the application parameters the procedure run’s with, then default param’s to ”

Create procedure [dbo].[GetPopulation]

        @CountryCode varchar(3),
    @State varchar(80)='',
    @City varchar(80)=''

select Population
FROM Countries
Where CountryCode = @CountryCode AND State = @State AND City=@City

Run the procedure as dbo.GetPopulation 'US' for US or

dbo.GetPopulation 'US','New York', 'New York City' for New York City