How to Refer value of another attribute value selected by user in different attribute's attribute ed

would like to refer the user selected asset type value and build the query, populate the ExistingTags attribute based on the value selected of asset type. How to refer the attribute value in the query asset or cselement of the query asset. Tried

String Attr_AssetType = ics.GetVar("Attribute_AssetType");

String A_AssetType = ics.GetVar("AssetTypeVC");

String A_AssetTypeVC = request.getParameter("AssetTypeVC");

but all gives null value.

//String sqlString = "SELECT distinct name as name1 from FW_Tag where resourcetype = '" + Attr_AssetType  + "' order by name"; (this is what I need to build in the query asset but it doesn't work as Attr_AssetType is not the rightway to get the attributevalue apperently.