Get date and time of max value

Question

I have a weather-reading database where I store all data for consumption by a webpage that shows the MAX and MIN pressure.

The problem is that I like to show the time and date in which these values where recorded.

Code I use to read MAX pressure:

$max_out_pressure = mysql_query("SELECT MAX(out_pressure) AS out_pressure FROM $table");
$max_out_pressure = mysql_result($max_out_pressure,0,"out_pressure");
$max_out_pressure = substr($max_out_pressure, 0, 6);
echo "$max_out_pressure";
echo "mbar";

I have the columns ID , Datetime , Pressure , Temperature Table is named readings

Webpage: http://temperatur.co.nf/readings.php

Never made an database or webpage before, so I`m struggling with this.

Answer 1

This will get the maximum pressure and the date it was recorded.

$sql = "SELECT out_pressure, Datetime
        FROM $table
        ORDER BY out_pressure DESC
        LIMIT 1";
$result = mysql_query($sql);
$row = mysql_fetch_assoc($result);
$max_out_pressure = $row['out_pressure'];
$max_date = $row['Datetime'];