Hi all, I am struck with this logic please someone help me

I was tying to calculate sum ( menge) material quantity when shkzg = 'S and 'H' rom AMDP class.

when i apply CASE condition it brings incorrect data that duplicate values even if i select distinct values .

i have sample code in ABAP but same i want it in AMDP class to use it in CDS table function.

fig2amdp.jpg