You mean there will be a value and you would like to add another value to the existing one as the idea of concatenation or what ..
Put the inputs and your expected output ..
Dim i%, strSql$
For i = 1 To Cells(Rows.Count, 1).End(xlUp).Row
strSql = "select mp.asin,mp.item_name from booker.d_mp_asins mp where mp.is_deleted = 'N' and mp.marketplace_id = '44571' and mp.asin =" & Worksheets("ASIN").Range("A" & i).Value