Mysql – Getting last row for each day in MySQL

MySQL

I have problem in selecting other columns for the max(datetime) records. In layman terms I need to get relevant columns where max(DialDateTime) records for all the dates in Mysql.

 mysql> select max(DialDateTime) as max from log_AP group by   date(DialDateTime) ;
 +---------------------+
 | max                 |
 +---------------------+
 | 2012-12-03 07:37:26 | 
 | 2012-12-04 07:37:04 | 
 | 2012-12-05 07:37:04 | 
 | 2012-12-06 07:37:04 | 
 | 2012-12-07 07:37:04 | 
 | 2012-12-08 07:37:04 | 
 | 2012-12-09 07:37:04 | 
 +---------------------+

7 rows in set (0.00 sec)

Best Answer

You should be able to use a subquery to get the max date and then join that to you table to return the remaining columns:

select a1.*
from log_AP a1
inner join
(
  select max(DialDateTime) as max 
  from log_AP 
  group by date(DialDateTime)
) a2
  on a1.DialDateTime = a2.max

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That suggests that your query should be

SELECT * 
FROM `stats`  
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Mysql – SQL Query to get last day of every week

You need to use the DAYOFWEEK function

If the End of the Week in Saturday, any date can be morphed into a Saturday.

For example, this computes the upcoming Saturday

SELECT DATE(NOW() + INTERVAL (7 - DAYOFWEEK(NOW())) DAY);

This computes the upcoming Sunday (you must use WEEKDAY function instead)

SELECT DATE(NOW() + INTERVAL (6 - WEEKDAY(NOW())) DAY);

For a table called mytable with a Date Column called theDate, your summation would be

Saturday

SELECT COUNT(1) DateCount,EndOfWeekDate FROM
(
    SELECT DATE(theDate + INTERVAL (7 - DAYOFWEEK(theDate)) DAY) EndOfWeekDate
    FROM mytable
) A GROUP BY EndOfWeekDate;

Sunday

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    FROM mytable
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Give it a Try !!!

CAVEAT if you want any other end of week other than Saturday and Sunday, I wrote an insane algorithm back in Sep 22, 2011 for computing any week starting and ending whatever day.

Best Answer

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