Question

event_date的类型为DATETIME，$date = '2014-11-07'

我可以运行查询

$this->Select(" * FROM events WHERE DATE(event_date) = ?",
                 array($date));

或

$this->Select(
      " * FROM events WHERE DATE_FORMAT(event_date,'%Y-%m-%d') = ?",
                 array($date));

但我会徘徊会导致它每行都执行日期操作吗？

也许最好使用

$this->Select(" * FROM events WHERE event_date = ?",
                 array($date. ' 00:00:00'));

代替？

Answer 1

显示上述问题的基准：

SELECT * FROM `test` WHERE date(event_date) ='2014-11-07' limit 0,10000;
--Showing rows 0 - 29 ( 10,000 total, Query took 0.0087 sec)

SELECT * FROM `test` WHERE date_format(event_date,'%Y-%m-%d') ='2014-11-07' limit 0,10000;
--Showing rows 0 - 29 ( 10,000 total, Query took 0.0119 sec)

SELECT * FROM `test` WHERE event_date   ='2014-11-07 00:00:00' limit 0,10000;
--Showing rows 0 - 29 ( 10,000 total, Query took 0.0076 sec)

输出如phpmyadmin

所示

WHERE子句中DATE或DATE_FORMAT的开销是多少？

1 个答案: