sql语句中的 case.. when...then ...else 用法

select (case when Symbol='正常' then cast(standard.minvalue as nvarchar(50)) +'-'+cast(standard.maxvalue as nvarchar(50))
else standard.Symbol end) as Symbol1 from ItemStandard as standard

case.. when...then ...else   sql语句中的判断方式 

cast(standard.minvalue as nvarchar(50))  将standard.minvalue 类型强转为 nvarchar(50) 类型