fixed value in table value range

hi,

if i write a z-program to upload data to table, may i know how to check the validity of data if the value is stored in the same table but inside the value range of 1 of the field.

for example, i want to upload data to table jxyz. in this table, there is a field called jfrm where the fixed value in this field is P, L and X.

how in the z-program i need to check. if the field value in the internal table to upload to jxyz-jfrm is not the value in the fixed value in value range.

normally we can check with master table but if the value is maintained in value range of the same table, what method i can use to check?

normally i use select single statement to check but i do not think i can use this to check value in value range.

i need to check the cirrectness of data before i use sql update to pump in the table.

please advise.

thanks