MS Access检查是否为空null

Question

I have the following table - Item and Sizes are the field names:

Item  Size1   Size2   Size3  Size4  Size5  Size6  Size7
ABY    S
XYZ    S       M       L      XL
FGH    8       10      12     14
QWE            4       5      6      7

But I need to arrive at the following:

Item     SizeRange
ABY        S
XYZ        S-XL
FGH        8-14
QWE        4-7

I can do this via a SWITCH function and checking where size <> '' however in reality the fields go up to size 15. Is there an easier, cleaner way to achieve this? ie VBA?

Regards,

Michael

Answer 1

If you redesign your table to this format:

Each size has a weight, or order value so you know which order they're used in.
This SQL, which may not be the best implementation (I'm a little rusty) will give the table shown in your example:

SELECT    T1.Item
        , MinSize & IIF(Not MaxSize Is Null,' - ' & MaxSize,'') AS SizeRange
        , MaxSize
FROM    (
            SELECT TOP 1      Item
                            , Size AS MinSize
            FROM              tbl_ItemSizes
            GROUP BY          Item
                            , Size
                            , Weighting
            ORDER BY          Weighting
        ) T1 LEFT JOIN
        (
            SELECT TOP 1      Item
                            , Size AS MaxSize
            FROM              tbl_ItemSizes
            GROUP BY          Item
                            , Size
                            , Weighting
            ORDER BY          Weighting DESC
        ) T2 ON T1.Item = T2.Item  

(Someone feel free to rewrite the SQL).