• You could try something like this (untested):

    Select HouseLine1 = (case when len(House_No_End) > 0 then House_No_Start + ' - ' + House_No_End

    when len(House_No_Start) > 0 then House_No_Start

    else House_Name end)

    If you haven't even tried to resolve your issue, please don't expect the hard-working volunteers here to waste their time providing links to answers which you could easily have found yourself.