MySQL time and date query methods and functions-Mysql Tutorial-php.cn

MySQL time and date query methods and functions

黄舟

Release： 2017-02-22 10:58:04

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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

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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(&#39;2011-10-27&#39;,&#39;2011-09-05&#39;) AS DiffDate;
+----------+
| DiffDate |
+----------+
|       52 |
+----------+
1 row in set

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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              |
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+------------------------------------+
24 rows in set

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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

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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

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

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

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

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