Table 1 (transaction table)
key - tran_id - unique id for this table.
Columns:
tran_id
member_id
Table 2 (member table)
Columns:
member_id
Every time a member does a transcation like deposit, its saved in transaction table.
data-table 1:
tran_id, member_id
1,1
2,1
3,1
4,1
5,2
6,2...