SAP HANA SQL

I Want to concat three fields,but The result of the method shown in the picture1 and picture2 is empty,Please Tell me how to correct it

Such as database table data:

fmsno service_o service_f service_m

fms01 0002 0015

fms02 0008

fms02 0003

the expect results:

fms01 service_type_zh1

fms01 a/c

fms02 b

fms03 a