Re: Assistance required for query with subquery

[Rick James]

"each unique AddressID is accompanied with lowest OrderID"

First, devise a JOIN to collect the data from the two tables. Then do a GROUP BY and MIN to get the desired result:

SELECT  p.AdresID, MIN(s.OrderID)
    FROM Sync_Orders AS s
    JOIN Sync_Phone  AS p  ON s.PhoneID = p.PhoneID
    GROUP BY p.AdresID

Unfortunately, that will not get you the corresponding Orderdate. That gets trickier...

SELECT AdresID, OrderID, Orderdate
    FROM (
        SELECT  p.AdresID, s.OrderID, s.Orderdate
            FROM Sync_Orders AS s
            JOIN Sync_Phone  AS p  ON s.PhoneID = p.PhoneID
            ORDER BY p.AdresId ASC, s.OrderID ASC   -- Sort the rows so that the MIN is first
         ) x  -- Gather all possible rows
    GROUP BY AdresID   -- This will pick the first row for each AdresId