How to add new data if not existing already

Hello,

I have data of all transaction of some members by their id in sheet1
and member id in sheet2.

I have to add data of new transaction in sheet1 on daily basis.
Now i have to check.

if member in new data is already in sheet2, then nothing to do. and if member of new data is not in sheet2 than add the member (only) in last row of sheet2 and so on.

Can you give me macro for this?