问当存在重载时，检查DB2上是否存在函数

EN

create function aaa.a_drop(in a integer, in b varchar(32)) 
returns integer 
begin 
return(1) 
end;

create function aaa.a_drop(in a varchar(32), in b integer)
returns integer 
begin 
return(1) 
end;

call aaa.drop_if_exists('aaa','a_drop',2,'integer,varchar(32)');
create function drop_if_exists(in v_schema varchar(128),in v_function_name varchar(128), in v_params_counter integer, in v_params_signature varchar(128) default null)
returns integer
begin
 declare v_count integer;--
 select count(1)
 into v_count
 from syscat.routines
 where ROUTINESCHEMA = v_schema
 and routinename = v_function_name
 and routinetype = 'f'
 and parm_count = v_params_counter
 return v_count;--
end;