从mysql迁移到GBase 8t数据库时，原有unix_timestamp()函数在GBase 8t中不可用，因此需要自己创建相应的函数，可以使用C或者JAVA创建自定义例程，也可以使用存储过程。以下以存储过程方式创建。

create procedure UNIX_TIMESTAMP(datestr datetime year to fraction(5)) 
returning  int;

  define srcdate datetime year to fraction(5);
  define rc_char varchar(30);
  define rc int;

  let srcdate = datetime(1970-01-01 00:00:00.00000)  year to fraction(5) ;
  let rc_char = datestr - srcdate;
  -- rc_char 17281 13:07:11.00000
  let rc = (substr(rc_char,1,9)*86400 + substr(rc_char,17,2)*1 + substr(rc_char,14,2)*60 + substr(rc_char,11,2)*3600)::integer;
  let rc = rc - 8*3600;

  return rc;
end procedure ;

create procedure UNIX_TIMESTAMP(datestr varchar(30)) 
returning  int;

  define srcdate datetime year to second;
  define tmpdate datetime year to second;
  define rc_char varchar(30);
  define rc int;

  let srcdate = datetime(1970-01-01 00:00:00)  year to second ;
  let tmpdate = to_date(datestr,'%Y-%m-%d %H:%M:%S');
  let rc_char = tmpdate - srcdate;
  -- rc_char 17281 13:07:11.00000
  let rc = (substr(rc_char,1,9)*86400 + substr(rc_char,17,2)*1 + substr(rc_char,14,2)*60 + substr(rc_char,11,2)*3600)::integer;
  let rc = rc - 8*3600;

  return rc;
end procedure ;