fix derivatives variable substitution

database/database_table.py

@@ -818,6 +818,7 @@ class DatabaseTable(Table):
 
         case = case.strip("~")      # doesn't need "~" anymore
         str_list = re.findall(r'("[\w]"|[\w.]+)', case)
+        print('-----------------\n',str_list,'\n--------------------')
         for substr in str_list:
             if '.' in substr:        # We have a var from another table
                 table = substr.split('.')[0]
@@ -836,7 +837,17 @@ class DatabaseTable(Table):
             var_target = self._get_variable_target(var_name.strip('"'), year)
             if var_target is not None:
                 var_db = self._protocol.dbcolumn_from_target(var_target)[0]
-                case = case.replace(var_name, var_db)
+                case_tokens = case.split(" ")
+                case_tokens = case.split(' ')
+                for i in range(0, len(case_tokens)):
+                    # remove everything prior to first, and after last quotation mark (including them)
+                    token_varname = re.sub(r'(^[^\"]*[\"])', '', case_tokens[i]) 
+                    token_varname = re.sub(r'([\"][^\"]*$)', '', token_varname)
+                    if (token_varname == var_name):
+                        case_tokens[i] = case_tokens[i].replace(var_name, var_db)
+                
+                ch = ' '
+                case = ch.join(case_tokens)
 
             if table is not self and table not in referred_tables:
                 referred_tables.append(table)