how to query access to select entire records given a distinct criteria

问题

I want to select the entire first row of each record where a promo code is unique. I am trying to create a samples table, in this table will be one record (the first record) from each distinct promo code. I have asked all of my co-workers and they usually go though the data by hand and select one from each. the problem is that the number of promo codes grows each time and the codes change. so I want to write a query that will select the first record found to have each distinct code. so for I have something like this:

SELECT DISTINCT Customer.promo1 FROM Customer AS promo;

SELECT * FROM Customer, promo
WHERE Customer.promo1 = promo.promo1;

But this obviously give the original table. I do have a ID field called AutoID in Customer.

Thanks in advance.

回答1:

I'm assuming you want the first Customer.AutoId associated with each Customer.Promo

SELECT
    c.*
FROM
    Customer  c 
    INNER JOIN 
    (

    SELECT 
        c.promo1,
        MIN(c.AutoID) AutoID
    FROM 
        Customer  c
    GROUP BY
        c.promo1) FirstCusomterWithPromo
    ON c.AutoID = FirstCusomterWithPromo.AutoID

回答2:

Something like that:

SELECT * FROM Customer
GROUP BY Customer.promo1 

来源：https://stackoverflow.com/questions/5953592/how-to-query-access-to-select-entire-records-given-a-distinct-criteria