Performance Issue, Is It Indexing?

Hi,





In SQL Server 2000, I have a table called SupplierData that has about 100000 records, and its structure looks like this:





CREATE TABLE [dbo].[SupplierData] (


[ID] [int] IDENTITY (1, 1) NOT NULL ,


[Supplier] [nvarchar] (30) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,


[Title] [nvarchar] (70) COLLATE SQL_Latin1_General_CP1_CI_AS NOT NULL ,


[Category] [nvarchar] (10) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,


[ItemID] [nvarchar] (30) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,


[UPC] [nvarchar] (30) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,


[Mftr] [nvarchar] (30) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,


[Genre] [nvarchar] (30) COLLATE SQL_Latin1_General_CP1_CI_AS NULL ,


[Retail] [smallmoney] NULL ,


[Cost] [smallmoney] NULL ,


[PreOrder] [smalldatetime] NULL ,


[Release] [smalldatetime] NULL ,


[Disc_FinalReturn] [smalldatetime] NULL ,


[GIS] [bit] NULL


) ON [PRIMARY]





Anyways, I recently imported some records (4000 or so) into it which didn't have a UPC Code (NULL) , Since then, all the Stored procedures in my database that use this table have been incredibly slow. I'm talking like things that used to take 2 minutes to run now take an hour.


I'm not really sure what is causing this, but since it work fine before I imported the records I have an idea that it has something to do with that.


I'm wondering if maybe since there was a index on UPC code, maybe it is choking on all the Nulls? I'm still just learning about the wonderful world of indexes.





The types of queries I'm running on this table are not that involved, mainly stuff like:





SELECT Cost, ItemID FROM SupplierData WHERE UPC = @UPC and Supplier = @SupplierName ORDER BY Cost


SELECT Top 1 Cost FROM SupplierData WHERE UPC = @UPC ORDER BY Cost





Any thoughts?





Thanks