declare
  ja_existe  exception;
  pragma exception_init (ja_existe  , -00001);
begin
  execute immediate 
  'insert into constante values (
        constante_seq.nextval, 
        ''URL_WS_AG'', 
        ''URL_WS_AG'',
        1,
        ''http://177.22.36.181:8081/cgi-bin/AGWS.exe/wsdl/IAG'', 
        1, 
        1,
        sysdate, 
        1)';
  exception when ja_existe  then null;
end;