相关疑难解决方法(0)

减去timestamps返回值时是interval数据类型.是否有一种优雅的方法可以将此值转换为间隔中的(毫秒/微秒)总数,即整数.

以下可行,但它不是很漂亮:

select abs( extract( second from interval_difference ) 
          + extract( minute from interval_difference ) * 60 
          + extract( hour from interval_difference ) * 60 * 60 
          + extract( day from interval_difference ) * 60 * 60 * 24
            )
  from ( select systimestamp - (systimestamp - 1) as interval_difference
           from dual )

SQL或PL/SQL中是否有更优雅的方法？

该管理员的要求作出解释的以下工作如何扔了一个点,这我不确定.

select sysdate + (interval_difference * 1440) - sysdate
  from (select systimestamp - (systimestamp - 1) as interval_difference
          from dual )

也就是说,加号还是减号都有运算符优先级？文档¹列出了运营商订单,如下所示

+----------------------------+-------------------------------------------+
| Operator                   |Operation                                  |
+------------------------------------------------------------------------+
| +, - (as unary operators)  | Identity, negation, location in hierarchy |
| , PRIOR, CONNECT_BY_ROOT   |                                           |
+----------------------------+-------------------------------------------+ 
| *, /                       | Multiplication, division                  |
+----------------------------+-------------------------------------------+
| +, - (as binary operators) | Addition, subtraction, concatenation      |
| , ||                       |                                           |
+----------------------------+-------------------------------------------+

查询一旦减少就变成了date …