Show value if different to selected

[elinamcastelletta]

Hello,

I need to get the values from D which are not assigned to a field in S:

S	A	D
1	x	x1
1	x	x2
1	b	b3
2	b	b4
2	x	x5
	x	x6
	x	x7

Example:

- No S selected. Result --> x6, x7 -Done: if( isnull(S),D)

-S=1 selected. Result -->b4,x5,x6,x7  - ?

-S=2 selected. Result --> x1,x2,b3,x6,x7 - ?