Translate a Stata loop into a SPSS loop

Could anyone help with the translation of the following Stata code? I need this code for further analysis in SPSS.

if year<1990 {
    bysort country year ID: egen sum080=sum(PY080g)
    gen hydisp=(HY020+sum080)*HY025
}
else gen hydisp=HY020*HY025

I tried to solve the problem with the following SPSS code:

DO IF year<1990.
   SORT CASES BY country year ID.
   COMPUTE sum080 = SUM(PY080g).
   COMPUTE hydisp=(HY020+sum080)*HY025.
ELSE. 
   COMPUTE hydisp=HY020*HY025.
END IF.
EXECUTE.

But this code appears to be wrong. Do you have any idea how to resolve the problem?

Solution

This particular use of egen in Stata can be replicated in SPSS by using the AGGREGATE command. Using Nick Cox's revised Stata code:

bysort country year ID: egen sum080 = sum(PY080g)
gen hydisp = (HY020 + sum080) * HY025 if year < 1990 
replace hydisp = HY020 * HY025 if year >= 1990

A synonymous set of code in SPSS would be:

AGGREGATE OUTFILE=* MODE=ADDVARIABLES
  /BREAK = country year ID
  /sum080 = SUM(PY080g).
DO IF Year < 1990.
  COMPUTE hydisp = (HY020+sum080)*HY025.
ELSE.
  COMPUTE hydisp = HY020*HY025.
END IF.