PHP and MySQL syntax
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Convert time stamp <--> the human readable time format
timestamp
now
the human readable time format ex: 2010-12-21 10:05:06
- php: echo date("Y-m-d H:i:s", time() ); //Convert the time stamp of current time to the human readable time format. Ex: return '2010-12-21 10:05:06'
- mysql:
- SELECT NOW(); /*return the human readable current time: 2011-04-01 12:19:43 */
- SELECT NOW()+0; //2011-04-01 12:19:43 returns 20110401122023.000000
- SELECT CURRENT_TIMESTAMP; /*return the human readable current time: 2011-04-01 12:19:43 */
the current timestamp ex: 1292897201
- php: echo time();
- mysql: SELECT UNIX_TIMESTAMP(); //2011-05-30 01:56:38 returns 1306720622
- javascript: datetime - How do you get a timestamp in JavaScript? - Stack Overflow [Last visited: 20110323]
compare the timestamp and human readable time format
SELECT UNIX_TIMESTAMP( ) , FROM_UNIXTIME( UNIX_TIMESTAMP( ) , '%Y-%m-%d %H:%i:%S' );
off topic
- DOS: date/t
output: OS in English: Thu 05/03/2012 OS in Chinese: 2012/05/03 星期四
specified time
the human readable time format ex: 2010-12-21 10:05:06
- php: echo date("y-m-d H:i:s", 1292897201 ); // convert the time stamp 1292897201 to the human readable time format
- mysql:
- SELECT FROM_UNIXTIME( 1306311155 ); //convert the time stamp 1306311155 to the human readable time format 2011-05-25 08:12:11
- SELECT FROM_UNIXTIME( 1306311155, '%Y-%m-%d %H:%i:%S' ); //convert the time stamp 1306311155 to the human readable time format 2011-05-25 08:12:11
convert human-readable time to timestamp
- php:strtotime()
- mysql: SELECT UNIX_TIMESTAMP('2011-03-15 18:53:57'); /* return timestamp: 1300186437 */
time difference of two time values
- php: using mktime() function
- mysql: SELECT TIMEDIFF('2010:01:01 00:00:00', '2010:02:01 00:00:00'); /* return -744:00:00 */
further reading
- PHP Date and Time functions
- MySQL The DATETIME, DATE, and TIMESTAMP Types
- MySQL Date and Time Functions
before delete trigger to make backup of deleted data
MySQL :: Re: before delete trigger to make backup of deleted data
step 1: create table hello_deleted_data with the same structure of table hello
step 2: add a trigger
create trigger hello before delete on hello for each row insert into hello_deleted_data (x,y,z) values (OLD.x, OLD.y, OLD.z);
tested on version: mysqlnd 5.0.7-dev - 091210
ideas
filter some records
- approach 1: (1) select * under some condition, (2) collect the $identifiers which matched the condition. and then (3) select some records NOT IN ( $identifiers )
- approach 2: (1) select * and then (2) unset some records which matched the condition.