Finding customers with identical orders

Question

I need to find customers who have made identical orders. (Using T-SQL)

Order

OrderID Customerer  
1   2   
2   5   
3   6            


        

Answer 1

This is an extension of Martin's second suggestion. This will show all matching combinations without any repetitions.

;With FmtOL(customer, orderid, complete_order) as
(            
SELECT  customer, orderid, complete_order
     FROM    Order O
                    cross apply ( SELECT    CAST(Quantity AS VARCHAR(30))
                                            + '~' + Reference + '~~'
                                  FROM      OrderLine OL
                                  WHERE     OL.OrderID = O.OrderID
                                  ORDER BY  Reference ,
                                            Quantity
                                FOR
                                  XML PATH('')
                                ) T ( complete_order )
)
SELECT  T1.OrderId, 
        T1.Customer,
        STUFF(C1.a, 1, 2, '') as [SameAs]
FROM    FmtOL T1
Cross apply ( SELECT '; ' + 'Customer ' + Cast(T2.Customer as varchar(30)) 
                  + '''s order ' + Cast(T2.OrderID as varchar(30))
                 FROM   FmtOL T2
                 WHERE  T1.Customer < T2.Customer
                   AND T1.OrderId < T2.OrderId
                   AND T1.complete_order = T2.complete_order
                 order by ';' + Cast(T2.Customer as varchar(30)) 
                    + '''s order ' + Cast(T2.OrderID as varchar(30))
                    , t2.orderid
                 for xml path('')
             ) C1 (a)
  where C1.a is not null

Results should look like this:

OrderId Customer SameAs 
1       2        Customer 6's order 3 
4       2        Customer 8's order 7