If both RESB and MCHB is maintained batch data for material, u can get it into an internal table. But if only one table has batch data and another doesn't have, then u cant na.
For eg. material ch_4100 is maintained batch data against it in MCHB. and in RESB its not maintained. Then u cannot get P order number Req. Quanitiy based on batch from RESB.
You will be connecting MCHB batch number with RESB batch number along with material and plant to get RESB AUFNR and BDMNG .
So if one table doesn't have batch number, then you cannot fetch batch number for that material.