How to make a single expression with certain condition

[#1]

Hi,

I hv two expression given below i need it to convert into single expression with certain condition.

i hv two fields PeriodName and SEMName.

if i select PeriodName field values then expression(1) to be executed.

if i select SEMName field values then expression(2) to be executed.

(1)Sum ({$<PeriodName={'$(=FIELDVALUE('PeriodName', FIELDINDEX('PeriodName', ONLY(PeriodName))-1))'}>}Values)

(2)Sum ({$<SEMName={'$(=FIELDVALUE('SEMName', FIELDINDEX('SEMName', ONLY(SEMName))-1))'}>}Values)

Pls help me out

[#2]

Hi,

You can try this:

=If(GetFieldSelections(PeriodName) > 0, Expression1, if (GetFieldSelections(SEMName) > 0, Expression2 ) )

[#3]

Its not working..the values not displayed