MySQL time and date query methods and functions

In MySQL applications, dates and queries are very common. For example, you want to check the data of a certain day, a certain week, or a certain month, query the number of days between two dates, query what day of the week a certain day is, etc. The following will introduce the related MySQL time and date functions and their specific usage.

NOW() function

Does MYSQL have a getdate() function like MSSQL? Yes, it's NOW().

mysql> SELECT now();
+---------------------+
| now()               |
+---------------------+
| 2011-10-27 09:49:42 |
+---------------------+
1 row in set

NOW() function returns the current date and time.

DATEDIFF() function

DATEDIFF() function returns the number of days between two dates.

DATEDIFF(expr,expr2)

DATEDIFF() Returns the number of days between the start time expr and the end time expr2. Expr and expr2 are dates or date-and-time expressions. Only the date portion of these values ​​is used in the calculation.

mysql> SELECT DATEDIFF('2011-10-27','2011-09-05') AS DiffDate;
+----------+
| DiffDate |
+----------+
|       52 |
+----------+
1 row in set

Query the data within a week

mysql> SELECT title FROM table WHERE datediff(FROM_UNIXTIME(date),now()) > -7;
+------------------------------------+
| title                         |
+------------------------------------+
| 什么是面向服务架构SOA              |
| 从菜鸟到编程高手的学习与认知历程   |
| JavaScript去除空格trim()的原生实现 |
| C语言程序在内存中的运行情况        |
| 为什么说Lisp到现在还很先进         |
| JavaScript截取中英文字符串         |
| 谈谈Javascript的匿名函数           |
| 程序员需要具备的一些基本技能       |
| 美国社会的一些潜规则               |
| 二叉搜索树的一些相关算法介绍       |
| JQuery仿淘宝滚动加载图片           |
| 收藏一些规范化输入输出的PHP函数    |
| 趣谈编程语言结构——函数             |
| CSS设计一个三列布局的页面          |
| 关于Android应用apk的程序签名       |
| JavaScript模拟打字效果             |
| 欧几里德算法（辗转相处法）练手     |
| JavaScript身份证号码有效性验证     |
| JavaScript对iframe的DOM操作        |
| 如何处理JSON中的特殊字符           |
| 一份腾讯2011笔试题                 |
| PHP如何实现异步数据调用            |
| 网站运营需要了解的一些规律         |
| 勤于思考才能善于架构               |
+------------------------------------+
24 rows in set

The same query can be used for a month, a year, or any number of days.

To query the day, you can write like this:

mysql> SELECT title FROM table WHERE datediff(FROM_UNIXTIME(date),now()) >= 0;
+----------------------------+
| post_title                 |
+----------------------------+
| 网站运营需要了解的一些规律 |
| 勤于思考才能善于架构       |
+----------------------------+
2 rows in set

To query the day of the week that a certain day is

DAYNAME(date)

Returns the name of the working day corresponding to date.

mysql> SELECT DAYNAME( NOW() );
+------------------+
| DAYNAME( NOW() ) |
+------------------+
| Thursday         |
+------------------+
1 row in set

To query what day of the week the date is, write this:

mysql> SELECT DAYOFWEEK( NOW() );
+--------------------+
| DAYOFWEEK( NOW() ) |
+--------------------+
|                  5 |
+--------------------+
1 row in set

Return the corresponding date (1 = Sunday, 2 = Monday, ..., 7 = Saturday) Weekday index. These index values ​​comply with ODBC standards.

The above is the content of MySQL time and date query methods and functions. For more related content, please pay attention to the PHP Chinese website (www.php.cn)!