Question

Let’s say that you are limited to use only this syntax (you can’t use aggregation functions like MAX or MIN, and neither you can’t use GROUP BY clauses; please don’t ask me why):

{SQL query} ::= SELECT [DISTINCT | ALL] [TOP {integer}]
                {select_list}
                FROM {table_reference}
                [WHERE {search_condition}]
                [ORDER BY {orderby} { ',' {orderby} } ]

Let’s say that we have an ITEM table, where the identifier is called ITEM_ID. For a given ITEM_ID you could have many rows with the same ITEM_ID but different SHIP_DATE. How would you write a query to return only the ITEMS with the most recent SHIP_DATE given the previous syntax?

I already tried using TOP N (to retrieve the first row in the result set) combined with an ORDER BY (to sort from the max SHIP_DATE to the min SHIP_DATE). Any ideas or suggestions?

What I tried is something like this:

SELECT TOP N * FROM ITEM WHERE ITEM_ID='X' ORDER BY SHIP_DATE DESC 

Actually the previous query seems to be working, but I’m wondering if there is a better way to do it.

This is not homework, I need to create a query using the supported FileNet P8 syntax: http://publib.boulder.ibm.com/infocenter/p8docs/v4r5m1/index.jsp?topic=/com.ibm.p8.doc/developer_help/content_engine_api/guide/query_sql_syntax_ref.htm

Answer 1

Assuming that ITEM.ship_date doesn’t fall on the same date for any other ITEM record:

  SELECT TOP x
         i.item_id,
         i.ship_date
    FROM ITEM i 
ORDER BY i.ship_date DESC

…where x is the number of unique/distinct ITEM.item_id records. How’d you’d get that without being able to use COUNT…

You have to use ORDER BY i.ship_date DESC in order to have the most recent ship_date records at the top of the result set.