docs: public String buildSQL() {
          mTables = new Hashtable();
          mColumns = new Vector();
  
          String key = null;
          for (Enumeration keys = mPropertiesMap.keys(); keys.hasMoreElements();) {
              key = (String) keys.nextElement();
      
              // Get columns to select
              String column = (String) mPropertiesMap.get(key);
              mColumns.addElement(column);
      
              tableJoins(column, false);
          }
  
          // All data read, build SQL query string
          return buildSelectClause() + buildFromClause() 
              + buildWhereClause(); 
      }