postgresql的now()与Oracle的sysdate区别说明

postgresql中的now()：
postgres=# begin ;
BEGIN
postgres=# select now();
  now  
-------------------------------
 2017-03-31 14:28:32.403869+08
(1 row)
 
postgres=# select now();
  now  
-------------------------------
 2017-03-31 14:28:32.403869+08
(1 row)
 
postgres=# select now();
  now  
-------------------------------
 2017-03-31 14:28:32.403869+08
(1 row)
 
postgres=# end;
COMMIT
 
postgres=# select now();
  now  
-------------------------------
 2017-03-31 14:28:54.917897+08
(1 row)
 
postgres=#

//在dao中这样写
member(name,pw,register_time)value("+DbAssitor.sdfyyyyMMddHHmmss.format(new Date())+"');";
//数据库助手类定义一个sdf类
public class DbAssitor
{
 /** 数据库相关操作中操作结果是没有影响行数 ***/
 public static int NO_AFFECT_ROW = 0;
 public static String sdfyyyyMMddHHmmss_ = "yyyy-MM-dd HH:mm:ss";
 public static SimpleDateFormat sdfyyyyMMddHHmmss = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
}