SELECT CASE 中缺少关键字答案

【问题标题】：Missing keyword from SELECT CASESELECT CASE 中缺少关键字
【发布时间】：2013-02-28 13:47:11
【问题描述】：

我不确定这一系列 case 语句有什么问题。我在网上查看过，语法似乎是正确的，但我收到了错误缺少关键字。任何帮助将不胜感激！

CASE 
when A = '1' then
         when sequence_number = 5 then 9
         when sequence_number = 6 then 9
         end
 when A = '2' then
       when sequence_number = 5 then 9
       when sequence_number = 6 then 9
       end
  when A = '3' then
        when sequence_number =7 then 9
        when sequence_number =8 then 9
        end
else T.number
end as number

【问题讨论】：

您需要在从属案例子句中添加一个额外的“案例”吗？即，当 A = '1' 时的情况，然后 case 当 sequence_number ... 等时
使用保留字 (number) 对列进行别名可能不是一个好主意。

标签： sql oracle select oracle10g case

【解决方案1】：

最简单的选择似乎是：

 case 
   when (A in (1,2) and sequence_number in (5,6)) or
        (A in (3  ) and sequence_number in (7,8))
   then 9
   else t.number
 end

【讨论】：

【解决方案2】：

@mikeb 是正确的 - 你需要一个额外的 CASE。

我在测试时也遇到了Number 列的问题；只是猜测，但也许甲骨文将其作为保留字窒息？如果您像我一样遇到ORA-01747: invalid user.table.column, table.column, or column specification 异常，请将其更改为Num 或TheNumber。

这是更新后的案例：

CASE
when A = '1' then
       case
       when sequence_number = 5 then 9
       when sequence_number = 6 then 9
       end
when A = '2' then
       case
       when sequence_number = 5 then 9
       when sequence_number = 6 then 9
       end
when A = '3' then
       case
       when sequence_number =7 then 9
       when sequence_number =8 then 9
       end
else T.number
end as number

【讨论】：

【解决方案3】：

您需要在每个分支中添加第二条 CASE 语句，或者您需要组合条件

CASE 
when A = '1' and sequence_number = 5 then 9
when A = '1' and sequence_number = 6 then 9
when A = '2' and sequence_number = 5 then 9
...
else T.number
end as number

或

CASE 
when A = '1' then
         case when sequence_number = 5 then 9
              when sequence_number = 6 then 9
         end
when A = '2' then
       case when sequence_number = 5 then 9
            when sequence_number = 6 then 9
       end
when A = '3' then
        case when sequence_number =7 then 9
             when sequence_number =8 then 9
        end
else T.number
end as number

【讨论】：