case - SQL - Creating A Conditional Where Clause For This Simple Query -

i've been trying create conditional clause query below keep seeing many alternatives i'm not sure use in case.

what need along lines of this: (though of course code wrong)

where cascasetype='m'   , cascurrentworkflowid=990   , cmsdatecreated between @fromdate , @todate   case @wfstatus       when @wfstatus=1 eveworkflowid<100       when @wfstatus=2 eveworkflowid<200       when @wfstatus=3 eveworkflowid<300       when @wfstatus=4 eveworkflowid<400  else 0  end 

so when choose wfstatus parameter 1, automatically engage section of clause bringing out results eveworkflowid less 100.

any appreciated!

thanks

where cascasetype='m'   , cascurrentworkflowid=990   , cmsdatecreated between @fromdate , @todate    , eveworkflowid <        case @wfstatus         when 1 100         when 2 200         when 3 300         when 4 400         else 0       end