Oracle-Apex树超过三层

Question

我用下面的sql代码在APEX中生成了一棵树：

select 1 as status, 1 pid, 'Fehlermeldungen' as titel, null as icon, '1' as value, NULL as tooltip, NULL as link from dual
union
select -1 as status, 2 pid, k.kname as titel, NULL as icon, k.knr||'0' as value, NULL as tooltip, NULL as link from kunde k where 
(select count(fmtext) from fehlermeldung f where f.knr = k.knr) > 0
union
select 0 as status, 3 pid, fmtext as titel, NULL as icon, k.knr||fmnr as value, NULL as tooltip, null as link from kunde k, fehlermeldung f where f.knr = k.knr
order by value

现在，我想添加第四层，但是如果我尝试使用pid = 4创建另一个联合，则该条目将附加到最后一个select。我该如何管理它呢？

Answer 1

首先，我尝试稍微重新格式化您的代码。看起来你所描述的应该可以正常工作。我假设你尝试过这样的东西：

select 1 as status, 1 pid, 'Fehlermeldungen' as titel, null as icon, '1' as value, 
       NULL as tooltip, NULL as link from dual
union
select -1 as status, 2 pid, k.kname as titel, NULL as icon, k.knr||'0' as value, 
       NULL as tooltip, NULL as link from kunde k 
where (select count(fmtext) from fehlermeldung f where f.knr = k.knr) > 0
union
select 0 as status, 3 pid, fmtext as titel, NULL as icon, k.knr||fmnr as value, 
       NULL as tooltip, null as link from kunde k, fehlermeldung f 
where f.knr = k.knr
-- begin my new lines...
union
select 0 as status, 4 pid, 'blank' as titel, NULL as icon, '4' as value, 
       NULL as tooltip, null as link from dual 
-- end my new lines...
order by 5

有没有可能你在错误的位置插入了额外的SELECT？向我们展示您做了什么，这样可以更轻松地进行故障排除。