Question

我有两张表const MyElement = (props) => { const thing = <span><li>Thing 1</li><li>Thing 2</li></span>; return ( <ul> <li>First</li> {condition ? thing.props.children : null} <li>Second</li> </ul> ); }和free_time。两者都包含tsranges。

如何在appointment中“减去”appointment的差异后，如何编写确定实际空闲时间的查询（或函数）？

freetime

我希望结果如下：

INSERT INTO free_time(freetime)
VALUES('[2017-04-19 09:00, 2017-04-19 12:30)');

INSERT INTO appointment(appointment)
VALUES('[2017-04-19 10:30, 2017-04-19 11:30)');

Answer 1

你必须从the docs

分开范围

如果结果范围需要包含两个不相交的子范围，则union和difference运算符将失败，因为无法表示这样的范围。

为此，您可以使用lower, and upper

SELECT tsrange(  lower(freetime), lower(appointment)  )  AS before_appointment,
       tsrange(  upper(appointment), upper(freetime)  )  AS after_appointment
FROM ( VALUES
  (
    '[2017-04-19 09:00, 2017-04-19 12:30)'::tsrange,
    '[2017-04-19 10:30, 2017-04-19 11:30)'::tsrange
  )
) AS t(freetime,appointment)
WHERE freetime @> appointment;

              before_appointment               |               after_appointment               
-----------------------------------------------+-----------------------------------------------
 ["2017-04-19 09:00:00","2017-04-19 10:30:00") | ["2017-04-19 11:30:00","2017-04-19 12:30:00")
(1 row)

Tsrange - 计算两个范围之间的差异

1 个答案: