What version of MySQL are you using? You have different options. http://dev.mysql.com/doc/mysql/en/Date_and_time_functions.html
Look at DATE_SUB() and SUBDATE()/SUBTIME().
The time part of the query would look something like DATE_FORMAT( DATE_SUB( NOW(), INTERVAL 4 HOUR ), '%H:%i:%s' ), or something like that.
Or, this might be better handled in Perl, just using Perl to control the time value supplied in the query -- I'm not sure about your "and so on". I wouldn't know how to handle a series of t1, t2, t3, t4, ..., tn without use of a scripting/programming language.
Wes
On Aug 18, 2004, at 3:44 PM, Viswanatha Rao wrote:
I have to select mysql rows based on the following condition. Time t1 = (current time - 4 hours); Time t2 = (current time - 8 hours); In my case, I want to select all those rows that have start times (1) between current time and t1 (2) between time t1 and t2 ... and so on
So I have to somehow subtract hours from the current time to get t1, t2,
and so on. In some other cases, I may have to subtract specific number
of minutes.
So my question is how do I selectively subtract hours or minutes from current time in mysql.
I need these values to plot a chart. Please let me know?
-----Original Message----- From: Wesley Furgiuele [mailto:[EMAIL PROTECTED] Sent: Wednesday, August 18, 2004 11:36 AM To: Viswanatha Rao Cc: [EMAIL PROTECTED] List Subject: Re: select rows by compare on datetime column
Vishwa:
Sorry -- I used a specific time value as an example, but since you were asking about current time, you would use CURTIME():
SELECT columns FROM table WHERE DATE_FORMAT( start_time, '%H:%i:%s' )= CURTIME() AND DATE_FORMAT( end_time, '%H:%i:%s' ) <= CURTIME();
Wes
On Aug 18, 2004, at 12:24 PM, Wesley Furgiuele wrote:
Does the date matter, or only the time?
If date matters (you want to find all records between 2004-06-01 10:00:00 AND 2004-06-03 18:00:00): SELECT columns FROM table WHERE start_time >= '2004-06-01 10:00:00' AND end_time <= '2004-06-03 18:00:00'
If only time matters( you want to find all records between 10:00:00 AND 18:00:00 on any day): --> If you're using version 4.1.1 or greater: SELECT columns FROM table WHERE TIME( start_time ) >= '10:00:00' AND TIME( end_time ) >= '18:00:00' --> Otherwise: SELECT columns FROM table WHERE DATE_FORMAT( start_time, '%H:%i:%s' )= '10:00:00' AND DATE_FORMAT( end_time, '%H:%i:%s' ) <= '18:00:00'
Wes
On Aug 18, 2004, at 11:39 AM, Viswanatha Rao wrote:
I have two columns in a table: start_time and end_time. Both are of types DATETIME When I select rows from table, I want to select only those rows where the current time falls between start_time and end_time
Can someone help with the SELECT syntax for this?
Best Regards Vishwa Rao
-- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
-- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
