PHP & SQL Task !

I am coding a renting website and I am almost done with the coding part except the interest calculation for each month. All I need from you is to help me with the Contract fields I am able to save them into the database but I need them also to be saved in another table and do the calculations with the interest rate. You can check [login to view URL] and view the fields I am talking about. Next, the thing I need is the rate [login to view URL] you can see there the fields I need and the calculations that need to be done. I need exactly the same fields done in SQL. I can also give you the website access if you want to check it by yourself. If I create a contract and add for example 24 months with the interest rate 8%, the data should be saved into 24 rows in the contract_installment table including the calculations with the interest rate you can also check [login to view URL] for the fields I need to be added into the contract_installment table. [login to view URL] is the current SQL table where the contract fields are stored. Contract Installment is the next database where the calculations with the interest rates and with the months should be saved to.