exclude values from field if exists in another field

[Daniel29195]

Hello all,

i have this data : 

my problem is that per product,  I want to get the sum of amountin column, for only the rows where  transid  doesnt exit in column refundid.

example:

transid = 1 , exists in the refundid column, thus the amountin for transid should be excluded from the sum.

i ve tried 

sum({

< transid= E({$ <transid={refundid}>})

,productid={1}>}

amountin)

but it didnt work,

any solution would be appreciated,

[Daniel29195 · Accepted solution]

i found the solution ,

sum({   <   transid -= {  $(=concat(if(refundid<>0,refundid),','))   },  productid={1}>}      amountin)