GET DENSE RANK WITHOUT RANK FUNCATION

set @rownum1:=0;
select AREA_ID ,
@rownum1:=(CASE WHEN (AREA_ID=@Tmax_18) THEN @rownum1+1 ELSE 1 END ) AS num1,(@Tmax_18:=AREA_ID) RANGE_SET
from 30Days_Forecast_File
where AREA_ID in (1,2)

 # AREA_ID, num1, RANGE_SET
'1', '1', '1'
'1', '2', '1'
'1', '3', '1'
'1', '4', '1'
'1', '5', '1'
'1', '6', '1'
'1', '7', '1'
'1', '8', '1'
'1', '9', '1'
'1', '10', '1'
'1', '11', '1'
'1', '12', '1'
'1', '13', '1'
'1', '14', '1'
'1', '15', '1'
'1', '16', '1'
'1', '17', '1'