Question

Duplicates in Table 1 are indentifies as follows;

select quote_ref, count (*) 
from table 1 
group by quote_ref 
having count(*) > 1 

Now I want the eliminate the duplicates based on the 2 rules below .

Take the entry that has the Status= Complete
If none in complete status then take the one with max([created_date ])
Else Flag to look at ?

Suppose I need a CASE statement with a delete, but not sure how to construct ?

Answer 1

For SQL Server 2005+, you can do the following:

;WITH CTE AS
(
    SELECT  *, 
            ROW_NUMBER() 
            OVER(PARTITION BY quote_ref 
                 ORDER BY CASE WHEN [Status]='COMPLETE' THEN 1 ELSE 2 END, 
                 created_date DESC) RowNum
    FROM table1
)
DELETE FROM CTE
WHERE RowNum != 1

In this case, I’m assuming that the row that you don’t want to delete is the one with status = 'COMPLETE' or the one with the maximum created_date. If is the other way around, you can simply change the WHERE condition.