Want to convert function in SQL Server 2000

Question

Hi ,
i am writing this function in oracle.Could you please convert this function in SQL Server 2000 because i am new in this and dont know how to use decode function in sql.
Please following is the code for oracle.
CREATE OR REPLACE function fun ( localex varchar2,titlex varchar2)
return number
as  x number;
begin
select sum ( decode (count (username),max(prereq_count),1,0) ) x into x from
   SELECT
                   prereq_count,
                   username
             FROM
                     table1
group by     username ;
return x;
end fun;
Regards
Vishal

Answer 1

Just take a look example below might give you idea :
create or replace function f_makeAddress_tx (
i_address_tx VARCHAR2,
i_city_tx VARCHAR2,
i_state_tx VARCHAR2,
i_zip_tx VARCHAR2)
return VARCHAR2
is
e_badZip EXCEPTION; u279E8
pragma EXCEPTION_init(e_badZip,-20998); u279E9
v_out_tx VARCHAR2(256);
begin
p_validateZip (i_zip_tx); u279E12
v_out_tx:= i_address_tx||u2019, u2018|| u279E13
i_city_tx ||u2019, u2018||
i_state_tx ||u2019, u2018||
i_zip_tx;
return v_out_tx; u279E17
exception
when e_badZip then u279E19
return i_zip_tx || u2018: Invalid zip code.u2019;
end;
Regards,
Clint