how to make a condition data column to equal decode date in oracle

Hi,

I have issue with my query to not let user enter a input value using a parameter a web browser in power bi server, because this not value in power yet

so so sad .

in this time i changed a lot of my old code to get this one

I am looking for a hit how to pass Data_g To not from only TO using a Colum in table with decode)

DECODE (c.paytyp, 1, c.CHKDAT_G, 2, c.PAYDAT_G) >'31/12/2018')

like in the pic

SELECT   

         Data_g,

         (SUM (NVL (actlon, 0)) + SUM (NVL (fees_paid, 0))

        - SUM (

             NVL (

                (SELECT  SUM (NVL (FEES_PAID, 0))

                   FROM loan50 c

                  WHERE     a.brnoff = c.brnoff

                        AND a.cntno = c.cntno

                        AND c.payflg = 1

                        AND 

                               DECODE (c.paytyp,  1, c.CHKDAT_G,  2, c.PAYDAT_G) >'31/12/2018'

                               ),

                0)))

         Sum_pay

  FROM lon1001 a

 WHERE     a.brnoff = f.brnoff(+)

       AND a.cntno = f.cntno(+)

       AND  a.brnoff = 0100 

       AND Data_g BETWEEN '01/01/2018' AND '31/12/2018'

       GROUP BY  

         Data_g,