Hi Ramki,
By using Case statement you can Achieve this,
CASE WHEN birth wait <'750 gram' then '1-A'
WHEN birth wait BETWEEN '751 gram' AND '1000 gram' THEN '1-B'
WHEN birth wait BETWEEN '1000 gram' AND '1500 gram' THEN '2'
WHEN birth wait BETWEEN '1501 gram' AND '2500 gram' THEN '3'
WHEN birth wait > '2501 gram' THEN '4'
END
Regards,
Samatha B