案例指令的 2 个结果

Question

为什么在这个查询中我得到两个使用大小写的结果？ 我以为在满足第一个条件之后，就会出现中断，而第二个根本不检查

select KOD from ap_magazyny mag where 1 =
    case 
    when (value1 like 'ZZ%' and mag.KOD like (select SUBSTR(value1,INSTR(value1,'/',1)+1,3) from dual)) then 1
    when (atrybut_t01 = value2 AND rownum = 1) then 1
    else 0
    end

结果喜欢

Answer 1

我希望我的例子会有所帮助：

with cte as (select case when id = 1 then
                       1
                  else 
                       2
                  end A 
           from test
           where rownum = 1) 
select *
from  test
join cte on test.id = cte.A

您需要将它连接到某个东西，因为 1 永远是 1，您将从表测试中获得所有结果。

DEMO

Answer 2

您可以使用 rownum=1 来限制结果。

select * from (
    select KOD 
      from ap_magazyny mag 
     where 1 = case when (value1 like 'ZZ%' 
                         and mag.KOD like (select SUBSTR(value1,INSTR(value1,'/',1)+1,3) 
                                             from dual)
                                           ) then 1
                    when (atrybut_t01 = value2 AND rownum = 1) then 1
                    else 0
               end
    order by case when (value1 like 'ZZ%' 
                         and mag.KOD like (select SUBSTR(value1,INSTR(value1,'/',1)+1,3) 
                                             from dual)
                                           ) then 1
                    when (atrybut_t01 = value2 AND rownum = 1) then 2
               end
)x
where rownum=1