Question

在Oracle下面，查询单列工作正常，但当我尝试将多列放入时失败，实际上我的要求是退出SQL查询，如果特定表中没有记录及其复杂的内部查询（下面是简化问题）我不能使用PL / SQL块，请建议。

SQL> select 
         case when (select count(*) from bl1_charge_adj where rownum=1) = '1' then ( select customer_id  from customer) 
         else 44 END as ee
     from dual;

EE
----------
44

SQL> select 
         case when (select count(*) from bl1_charge_adj where rownum=1) = '1' then ( select customer_id,DL_UPDATE_STAMP from customer) 
         else (1,2) END 
     from dual

第1行的错误：
ORA-00907：缺少右括号

Answer 1

我想你想要这样的东西：

select customer_id, DL_UPDATE_STAMP
from customer
where exists (select 1 from bl1_charge_adj)
union all
select 1, 2
from dual
where not exists (select 1 from bl1_charge_adj);

Answer 2

这应该有效：

select nvl(c.customer_id, 1), nvl(c.DL_UPDATE_STAMP, 2)
from ( select count(*) as c from bl1_charge_adj where rownum=1) d
left outer join customer c on d.c = 1;

我怀疑如果count(*)表很大，将bl1_charge_adj更改为其他内容会更好。

Oracle CASE在Else子句中

2 个答案: