I am building a billing OLTP database to hold our provider charges. Currently I have set the database up so that the charges are split into two tables: Services table (for fixed charges) and Usage table (for call charges).
Because both of these tables share many columns such as; the asset it is allocated to, the division the charge is related to, the charge description, the date, the cost and the rerated cost, I am seriously considering merging the two into a charges table. I feel this would help as summing the cost column would be the correct bill total rather than having to add the service cost to the usage cost. The only problem I can see with this is that they do differ on some columns and the calls table is vastly larger than the services table. Also calls can be treated slightly differently in analysis and reporting. Nevertheless as long as these can be split out I cant see this being a problem.
Is merging these table the right thing to do at the OLTP level?
Thanks in advance for any help.