The specific SQL that you will need will depend on some more details about your structure. You have a sizes table that has a cat id, but how does this cat id relate to the items sizeID? Does the sizeID column in your items table directly correspond to the SizeCatID column of the sizes table?
Also, does this mean that you have multiple items that are the same but have different SizeID's? An example of the all the columns in the tables involved would help to clear this up.
For your details page you should have a recordset that joins the items and sizes tables, and filters on the id for the selected item. How this is formed though will depend on the details mentioned above.
