Validations

Hi,

Iam doing some validations.fileds is plant(WERKS)mateial(MATNR), ZDATBA(date from date),ZDATBI(Date to date),Zmessage.

My requirement is

1)check whether a material is selected for the given plant.if it doesn't belongs to the selected plant,display error message" Material does not

exist for this plant"

2) Check whether the message entered already exist for the plant,material,Date

Combination(Note: All fields in ZMSG table).If it exists display message " A message already exists for the material,plant,date combination"

How to write the select quires for my requirement.Please help me.It is very urgent.

Thanks & Regards,

Sairam