sql - TSQL 上的 select 语句中的前 1 个案例

Question

我在这个查询上有问题。我怎样才能解决这个问题：

select (select case top 1 STATUS 
       when 'Inprocess' then 'Processing' 
       when 'Inworkbin' then 'Waiting In Draft' 
       end 
    from ICS_EMAIL_CONNECTIONS_TRX A    
    where A.SESSIONID = B.SESSIONID 
    and STATUS <> 'Completed'
    order by A.CREATE_DATE desc) as LAST_STATUS 

我收到此错误：

关键字“top”附近的语法不正确。

有什么建议么？

Answer 1

尝试：

select top 1 case STATUS

代替

select case top 1 STATUS 

Answer 2

您不需要嵌套选择。

select top 1 case STATUS 
             when 'Inprocess' then 'Processing' 
             when 'Inworkbin' then 'Waiting In Draft' 
             end LAST_STATUS
from ICS_EMAIL_CONNECTIONS_TRX A    
where A.SESSIONID = B.SESSIONID 
and STATUS <> 'Completed'
order by A.CREATE_DATE desc;

尽管这可以返回 0 行，而正确编写 TOP 1 的原始表单将始终返回一行，即使值为 NULL。

Answer 3

select (select top 1 (case STATUS 
   when 'Inprocess' then 'Processing' 
   when 'Inworkbin' then 'Waiting In Draft' 
   end) 
from ICS_EMAIL_CONNECTIONS_TRX A    
where A.SESSIONID = B.SESSIONID 
and STATUS <> 'Completed'
order by A.CREATE_DATE desc) as LAST_STATUS 

Answer 4

更正大小写和顶级关键字

select (select top 1 case STATUS 
       when 'Inprocess' then 'Processing' 
       when 'Inworkbin' then 'Waiting In Draft' 
       end 
    from ICS_EMAIL_CONNECTIONS_TRX A    
    where A.SESSIONID = B.SESSIONID 
    and STATUS <> 'Completed'
    order by A.CREATE_DATE desc) as LAST_STATUS 

Answer 5

select top 1 * from (select case STATUS 
       when 'Inprocess' then 'Processing' 
       when 'Inworkbin' then 'Waiting In Draft' 
       end 
    from ICS_EMAIL_CONNECTIONS_TRX A    
    where A.SESSIONID = B.SESSIONID 
    and STATUS <> 'Completed'
    order by A.CREATE_DATE desc) as LAST_STATUS