sql/coldfusion delete duplicate rows

问题

Here is my table

Display          UPC
0                0553406259120
0                0753406259120
1                0753406259120
1                0453406259120

If you notice, row 2 and 3 have the same UPC. I would like to delete all rows that have display = 0 and duplicate upc. So in my table I want to delete row 2 only. Here is my coldfusion code so far that doesn't work. Please advice.

<cfquery name="GetData" datasource="#Application.ds#" dbtype="ODBC" username="#Application.UserName#" password="#Application.Password#">
DELETE UPC
FROM products
WHERE DISPLAY = 0
GROUP BY UPC  
HAVING COUNT(*)>1
</cfquery>

回答1:

Assuming that you want to delete all rows where UPC is the same, but Display is different:

DELETE FROM Products as a
WHERE display = 0
AND EXISTS (SELECT '1'
            FROM Products as b
            WHERE b.display <> 0
            AND b.upc = a.upc)

This should work on all RDBMSs, and will remove all rows where UPC is the same, but with a different Display codes.

回答2:

DELETE FROM Products
WHERE DISPLAY = 0 
AND UPC in (SELECT UPC
            FROM Products
            GROUP BY UPC
            HAVING COUNT(UPC)>1)

来源：https://stackoverflow.com/questions/10289032/sql-coldfusion-delete-duplicate-rows