错误码：-4596
错误内容：此查询表达式不允许 FOR UPDATE

原因：带有派生表的子查询SQL无法进行select for update，达梦默认为不可更新视图，因此报错。

示例：

select * from
       (select e.ename as ename,
               e.sal   as sal  ,
               d.dname as dname
        from emp e
        left join dept d
        on e.deptno=d.deptno
       ) t
where sal>1000 for update;

问题处理：调整参数view_pullup_flag=2，对包含别名和同名列的视图进行上拉优化

select /*+ view_pullup_flag(2)*/ * from
       (select e.ename as ename,
               e.sal   as sal  ,
               d.dname as dname
        from emp e
        left join dept d
        on e.deptno=d.deptno
       ) t
where sal>1000 for update;