EXEC retrieve_customers_by_location 'Seattle','WA','98144','USA'

CREATE PROC retrieve_customers_by_location(
		@city	NVARCHAR(100),
		@state NVARCHAR(2),
		@zip NVARCHAR(9),
		@country NVARCHAR(10)
	)
	As

	Begin

	select * from customers where city=@city and state=@state and zip=@zip and country = @country

	End


select * from customers
		where
		(city = @city or @city is null) and
		(state= @state or @state is null) and
		(zip = @zip or @zip is null) and
		(country = @country or @country is null)

ID
FIRST
LAST
CITY
STATE
ZIP
COUNTRY
1
Joe
Public
Seattle
WA
98144
USA
2
Jane
Public
Amsterdam
BT
1063
NLD
3
Jennifer
Public
Miami
FL
33101
NULL