如何将varchar转换为uniqueidentifier

Question

我想将varchar转换为唯一标识符，以将其连接到另一个表。

是varchar60

select b.ServiceName,
       a.ServiceDetailsID,
       c.Description,sum(a.quantity * a.unitcost) as Amount
from cashexpenses a
inner join 
   ServiceDetails b
   on a.ServiceDetailsID = b.ServiceDetailsID
left join CashExpensesMaint c
   on convert( uniqueidentifier,a.Description) = c.CemID
where a.ServiceDetailsID in 
    (select ServiceDetailsID
      from ServiceDetails
      where MarginAnalysisID =@marginalanalysisid)
group by a.ServiceDetailsID,c.Description, b.ServiceName