select case
when
        "%CM0034%" = "<30"
then
        "Negative"
when
        ISNUMERIC("%CM0034%") = 1
then
        case
        when
                CONVERT(float,"%CM0034%") between 30.0
        and 300.0
        then
                "Trace"
        else
                "N/A"
        end
when
        "%CM0034%" = ">300"
then
        "Positive"
else
        "N/A"
end