docs: String buildIdentitySQL(String[] pKeys) {
          mTables = new Hashtable();
          mColumns = new Vector();
  
          // Get columns to select
          mColumns.addElement(getPrimaryKey());
  
          // Get tables to select (and join) from and their joins 
          tableJoins(null, false);
  
          for (int i = 0; i < pKeys.length; i++) {
              tableJoins(getColumn(pKeys[i]), true);
          }
  
          // All data read, build SQL query string
          return "SELECT " + getPrimaryKey() + " " + buildFromClause() 
              + buildWhereClause(); 
      }