Can I have a primary key as a non-unique column

Question

Hi all,
I have a table with 35 columns and only one column in a not null column. But this column data is not unique. I want to create a primary key with non-unique index, can I don it, if it is not possible is there any other way to it. Please help me with this.
Thanks for your help.vinaykotha

Answer 1

1) Do the 'Unique Column combination' check first, using this example. (Pl. Change the column name and number of columns you consider as candidate key.) The SQL as follows:-
;WITH CTE (ProductKey, CustomerKey, SalesTerritoryKey, DupRec)
 AS
  (SELECT ProductKey, CustomerKey, SalesTerritoryKey, ROW_NUMBER() OVER
     (PARTITION BY ProductKey, CustomerKey, SalesTerritoryKey
      ORDER BY ProductKey, CustomerKey, SalesTerritoryKey) AS DupRec
   FROM dbo.FactSales 
SELECT *
FROM CTE
WHERE DupRec > 1
2) if CTE Table returns no records, you are good to create a Composite CLUSTERED PRIMARY KEY, like:
ALTER TABLE dbo.FactSales
ADD CONSTRAINT PK_ProductKey_CustomerKey_SalesTerritoryKey 
PRIMARY KEY CLUSTERED (ProductKey, CustomerKey, SalesTerritoryKey);
If no error..bingo! if NOT, Don't worry, create a Composite Index like this:-
3)
CREATE NONCLUSTERED INDEX [IX_ProductKey_CustomerKey_SalesTerritoryKey] 
ON dbo.FactSales(ProductKey, CustomerKey, SalesTerritoryKey);
This will work still efficiently. Usually all transaction table are like that like Daily_Order table, Ship_Details table etc.
-NC