Question

I have a MS access table with the following columns and sample records.

How do I update the adDate value with the least LastSaleDate for each ProductID.

orderID productID   lastsaleDate    adDate
1       1           10/20/2012  
2       1           5/10/2007   
3       1           4/1/2004    
4       1           20/11/2011  
5       2           10/10/2010  
6       2           12/10/1972  

For example the adDate for ProductID 1 will be 4/1/2004
and for ProductID 2 will be 12/10/1972

Answer 1

Unless you have a compelling reason to actually store adDate values in your table, consider simply computing adDate with a query any time you need it. That way you don’t risk ever displaying adDate values which have not been updated to reflect the latest changes to the underlying data.

SELECT
    y.orderID,
    y.productID,
    y.lastsaleDate,
    sub.adDate
FROM
    YourTable AS y
    INNER JOIN
    (
        SELECT productID, Min(lastsaleDate) AS adDate
        FROM YourTable
        GROUP BY productID
    ) AS sub
    ON y.productID = sub.productID;