public static SPFieldLookupValueCollection GetLookFieldIDS(string lookupValues, SPList lookupSourceList)
 {
     SPFieldLookupValueCollection lookupIds = new SPFieldLookupValueCollection();
     string[] lookups = lookupValues.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
     foreach (string lookupValue in lookups)
     {
         SPQuery query = new Microsoft.SharePoint.SPQuery();
         query.Query = String.Format("<Where><Eq><FieldRef Name='Title'/><Value Type='Text'>{0}</Value></Eq></Where>", lookupValue);
         SPListItemCollection listItems = lookupSourceList.GetItems(query);
         foreach (Microsoft.SharePoint.SPListItem item in listItems)
         {
             SPFieldLookupValue value = new SPFieldLookupValue(item.ID.ToString());
             lookupIds.Add(value);
             break;
         }
     }
     return lookupIds;
 }
        public static SPFieldLookupValueCollection GetLookFieldIDS(string lookupValues, SPList lookupSourceList)
        {
            SPFieldLookupValueCollection lookupIds = new SPFieldLookupValueCollection();

            string[] lookups = lookupValues.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
            foreach (string lookupValue in lookups)
            {
                SPQuery query = new Microsoft.SharePoint.SPQuery();
                query.Query = String.Format("<Where><Eq><FieldRef Name='Title'/><Value Type='Text'>{0}</Value></Eq></Where>", lookupValue);
                SPListItemCollection listItems = lookupSourceList.GetItems(query);
                foreach (Microsoft.SharePoint.SPListItem item in listItems)
                {
                    SPFieldLookupValue value = new SPFieldLookupValue(item.ID.ToString());
                    lookupIds.Add(value);
                    break;
                }
            }
            return(lookupIds);
        }