php mysql date operation function_PHP tutorial

The article uses two examples to analyze and introduce the usage and format of PHP dates and MySQL dates. It also includes the field types and query efficiency tests used when MySQL uses dates.

php

int value:
time(): returns the number of seconds since the Unix epoch (00:00:00 Greenwich Mean Time on January 1, 1970) to the current time.
If we want to get the number of seconds from January 1, 1970 to 2012-2-10, we can use strtotime(): that is: strtotime('2012-2-10');
date value:

string date ( string format [, int timestamp] )

For the date() function, please refer to http://www.bKjia.c0m/phper/php-function/38146.htm

For example: directly date() returns the current time, of course we can specify its format:

For example date('Y-m-d',strtotime('2012-2-10'));
Time operation:

The code is as follows

Copy code

date('Y-m-d h:i:s' ,strtotime('+1 week'));  代码如下 复制代码 date('Y-m-d h:i:s',strtotime('+1 week')); date('Y-m-d h:i:s',strtotime('+5 hours')); date('Y-m-d h:i:s',strtotime('next Monday)); date('Y-m-d h:i:s',strtotime('last Sunday')); date('Y-m-d h:i:s',strtotime('+ 1 day',12313223));!!详见 int strtotime ( string time [, int now] ) date('Y-m-d h:i:s',strtotime('+5 hours')); date('Y-m-d h:i:s',strtotime('next Monday)); date('Y-m-d h:i:s',strtotime('last Sunday')); date('Y-m-d h:i:s',strtotime('+ 1 day',12313223));!! See int strtotime ( string time [, int now] )

Date parameters

The format of each parameter is represented separately:
a - "am" or "pm"
a - "am" or "pm"
d - day, two digits, if there are less than two digits, add zeros in front; for example: "01" to "31"
d - day of the week, three English letters; such as: "fri"
f - month, full English name; such as: "january"
h - hour in 12-hour format; e.g.: "01" to "12"
h - hour in 24-hour format; e.g.: "00" to "23"
g - hour in 12-hour format, no zeros are added if there are less than two digits; such as: "1" to 12"
g - hour in 24-hour format, no zeros are added if there are less than two digits; such as: "0" to "23"
i - minute; e.g.: "00" to "59"
j - day, two digits, if there are less than two digits, do not add zeros; for example: "1" to "31"
l - day of the week, full English name; such as: "friday"
m - month, two digits, if there are less than two digits, add zeros in front; such as: "01" to "12"
n - month, two digits, if there are less than two digits, no zero will be added; for example: "1" to "12"
m - month, three English letters; such as: "jan"
s - seconds; e.g.: "00" to "59"
s - add an English ordinal number at the end of the word, two English letters; such as: "th", "nd"
t - the number of days in the specified month; such as: "28" to "31"
u - Total seconds
w - Numeric day of the week, such as: "0" (Sunday) to "6" (Saturday) y - year, four digits; such as: "1999"

y - year, two digits; such as: "99"
z - day of the year; e.g.: "0" to "365"

For other characters not listed above, list the character directly

代码如下	复制代码
int->datetime select from_unixtime(int_time) from table; datetime->int; select unix_timestamp(date_time) from table;

(2)mysql:

代码如下	复制代码
select dayofweek('2012-2-2');返回一个星期的第几天 select dayofmonth('2012-2-2');返回一月中的第几天 select dayofyear('2012-2-2');返回一年中的第几天

The code is as follows	Copy code
int->datetime select from_unixtime(int_time) from table; datetime->int; select unix_timestamp(date_time) from table;

Time operation:

The code is as follows	Copy code
select dayofweek('2012-2-2' );Returns the day of the week select dayofmonth('2012-2-2'); Returns the day of the month select dayofyear('2012-2-2'); Returns the day of the year

Similar functions: month() day() hour() week()......
+days date_add(date,interval 2 days);
-How many days date_sub(date,interval 2 days);
Time format:
date_format(date,format)
select DATE_FORMAT('1997-10-04 22:23:00','%W %M %Y');
Other functions: TIME_TO_SEC() SEC_TO_TIME()...

Finally, let’s summarize the query efficiency comparison of using int, varchar, and datetime in the database when using time.

Test the update of four tables, update 100 records respectively, and record the time: Beijing PHP Resource Sharing Portal d*V.~ x G/Q O

Table 1: Page running time: 2.62180089951 seconds (non-fixed length, int time) Beijing PHP Resource Sharing Portal

Table 2: Page running time: 2.5475358963 seconds (fixed length, int time)
Table 3: Page running time: 2.45077300072 seconds (varchar, datetime time)

Table 4: Page running time: 2.82798409462 seconds (char, datetime time)

Under large data volumes, if there are a large number of queries such as select * from table where time >XX, it makes sense to use int for datetime in MySQL 5.1.

php mysql date comparison code
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