Question

SELECT top 1 
    case 
        when VR = -99999.99 
        then 0 
        else cast((VR*1.732) as decimal(38,3)) 
    end 
FROM pseb.dbo.datasource 
where FeederID=5003
order by datetime desc

The above query is working fine, but I need to return varchar value ‘–‘ instead of returning 0

if I do like that

SELECT top 1 
    case 
        when VR = -99999.99 
        then '--' 
        else cast((VR*1.732) as decimal(38,3)) 
    end 
FROM pseb.dbo.datasource 
where FeederID=5003
order by datetime desc

means it returns the following error:

Msg 8114, Level 16, State 5, Line 1 Error converting data type varchar
to numeric.

please help me to solve it

Answer 1

The problem is that you are returning two different data types from the same column. The rule with SQL Server that numeric types take precedence over string types, i.e. in a situation like yours a string gets converted to a number, not the other way around.

So to solve this you can cast your number to a string.

One option is to do something like this:

SELECT top 1 
   case when VR = -99999.99 then '--' 
    else 
     cast
      ( 
        cast((VR*1.732) as decimal(38,3)
      ) 
     as varchar(50)) 
    end 
  FROM pseb.dbo.datasource where FeederID=5003 order by datetime desc