按天获取统计信息-datetime列-MySQL / PHP

Question

I have an issue that I can't solve by myself. The best thing would be if it's possible to do it directly from mysql but if not, calculating from php is also good.

I have a table that has 3 columns: id, time, value

Now the time value is datetime (example: 2012-11-03 00:13:12)

I want to create statistics from the last 7 days. Let's say I have 7 rows and today is 2012-12-20.

Here are the rows: datetime value
2012-12-20 00:12:12 2
2012-12-20 04:06:15 4
2012-12-20 03:12:14 5
2012-12-18 03:12:14 7
2012-12-16 12:12:14 3
2012-12-16 14:23:34 2
2012-12-15 14:23:34 9

If I want to get the last 7 days report, it would be this:

2012-12-14 -> value =0
2012-12-15 -> value =9

2012-12-16 -> value =5

2012-12-17 -> value =0

2012-12-18 -> value =7
2012-12-19 -> value =0

2012-12-20 -> value =11

Currently I have this (extract last 7 day records):

$date=date("Y-m-d");
$date=date ("Y-m-d", strtotime ( '-7 day' . $date ) );  
$qry="select value,date from mytable where date>'$date'";
$res=mysql_query($qry) or die("Couldn't select Information : ".mysql_error());
while($row=mysql_fetch_array($res))
    {
        echo $row["value"];
    }

I hope somebody can help with advice. Thanks in advance! Vlad

Answer 1

This should be relatively easy to solve using just MySQL. This is very similar to this question: MySQL Query GROUP BY day / month / year

You need to change your query so it gets all the records for a given week.

SELECT DAY(date) , SUM(value)
FROM mytable
WHERE WEEK(date) = WEEK(NOW())
GROUP BY DAY(date)

Its also very easy to change how you group the numbers, for example by month using GROUP BY MONTH(date) . You could also make the MySQL display the day name as a field by doing SELECT DAYNAME(date) For more details on what functions are available check out the MySQL User Guide on Date and Time functions .