PPMT Function (Principal Payment) - SQL Server

PPMT.sql

/** 
 * Principal Payment
 * (SQL Server) 
 * AzsaturnDx (2020) - No copyright at all
 *
 * Returns the payment on the principal for a given period for an investment based on periodic, constant payments and a constant interest rate.
 *
 * @Rate FLOAT - Required. The interest rate per period.
 * @Period INT - Required. Specifies the period and must be in the range 1 to nper.
 * @Periods INT - Required. The total number of payment periods in an annuity.
 * @Present FLOAT - Required. The present value — the total amount that a series of future payments is worth now.
 * @Future FLOAT - Optional. The future value, or a cash balance you want to attain after the last payment is made. If don't needed pass 0 as value
 * @Type - Optional. The number 0 or 1 and indicates when payments are due.
 * @return FLOAT Payment on the principal for a given period
 *
 * @Example
 * 	  SELECT dbo.PPMT(0.4,12,24,0,20000,0)
 *
 * REQUIRES: dbo.IPMT
 * Required functions are available @: https://gist.github.com/Azsaturndx/8ce3e47e2d3210a65fc83b09ac32da5f
 */

CREATE FUNCTION [dbo].[PPMT]
	(@Rate Float
	,@Period INT
	,@Periods INT
	,@Present Float
	,@Future Float
	,@Type INT)  
RETURNS Float
    BEGIN   
        RETURN dbo.PMT(@Rate,@Periods,@Present,@Future,@Type) - dbo.IPMT(@Rate,@Period,@Periods,@Present,@Future,@Type)
    END;