你似乎认为你需要使用nvarchar。但事实未必如此。如果你能把你的小时数存储为十进制。解决办法很简单

hours = days * 24

如果你想把它分解成小时分和秒，你需要把它转换成秒。一天有24小时，一小时有60分钟，一分钟有60秒。

seconds = days * 24 * 60 * 60

一旦有了秒数，就可以使用除法运算符（/）和模运算符（%）。如果你把你的日子存储为十进制（3，1），你就不用担心秒了，因为分辨率太低了。

select 
 days
 ,CAST(days * 24 * 60 * 60 as int) as totalseconds --days converted to full seconds
 ,CAST(days * 24 * 60 as int) as totalminutes --days converted to full minutes
 ,CAST(days * 24  as int) as totalfullhours --days converted to full hours
 ,CAST(days * 24 * 60 as int) % 60 as remainingminutes -- since the row above contains full hours, we need to find out how many minutes are in the split hours f ex 0.2 hours
 ,CAST(days * 24 * 60 * 60 as int) % 60 as remainingseconds -- this will always be 0 because of your precision
from YourTable

如果您仍然希望结果是单个字符串列（hh：：mm），那么它将是

select 
     CAST(CAST(days * 24  as int) as varchar(10)) + ':' + RIGHT('0'+CAST(CAST(days * 24 * 60 as int) % 60 as varchar(10)),2) 
    from YourTable