In my earlier article, I implemented a lot of excel financial functions including PMT function using CLR and I found CLR implementation is the effective way to implement excel functions in SQL Server. However you can develop the same functionality in SQL using User Defined Function as well.
Given below is the script of PMT financial function in SQL Server with examples. Basically PMT function not only calculates the future value of any investment on an interest rate, it also calculates the payments for a loan.
Appreciate your valuable feedback about this function.