join update 처리방법입니다.(연관성 있는 테이블을 조인하여 처리하는 UPDATE 구문)

   //특정 테이블 UPDATE
            StringBuffer sql = new StringBuffer();
            sql.append( " SELECT A.NEW_DATA, B.OLD_DATA     "  );
            sql.append( " FROM JOIN_TABLE A, TARGET_TABLE B "  );
            sql.append( "  WHERE A.TABLE_KEY = B.OLD_DATA   "  );
           
            PreparedStatement pstmt = conn1.prepareStatement(sql.toString());
            rs = pstmt.executeQuery();
           
            StringBuffer updateSql = new StringBuffer();
            updateSql.append( " UPDATE TARGET_TABLE SET OLD_DATA = ? WHERE OLD_DATA = ? " );

            PreparedStatement updatePstmt = null;
            while(rs.next()) {
                updatePstmt = conn2.prepareStatement(updateSql.toString());
                updatePstmt.setString(1, rs.getString(1));  // A.NEW_DATA
                updatePstmt.setString(2, rs.getString(2));  // B.OLD_DATA
                updatePstmt.executeUpdate();
                updatePstmt.close();
            }
            rs.close();
            pstmt.close();