How to get average value based on user selection?

[xhkmx]

I manage to display data using below query that will show value for each month. How to calculate average value starting july onwards(based on user selection).

 

Let say the value for element 'A'  are Jul=80, Aug= 80, Sep=90. If user select Aug then the average is 80 and if user select Sep then the average is 83.

 

Query:

$sql2 = "Select element,
	SUM(CASE WHEN Month = 'Jan' THEN total ELSE 0 END ) AS Jan,
	SUM(CASE WHEN Month = 'Feb' THEN total ELSE 0 END ) AS Feb,
	SUM(CASE WHEN Month = 'Mac' THEN total ELSE 0 END ) AS Mac,
	SUM(CASE WHEN Month = 'Apr' THEN total ELSE 0 END ) AS Apr,
	SUM(CASE WHEN Month = 'May' THEN total ELSE 0 END ) AS May,
	SUM(CASE WHEN Month = 'Jun' THEN total ELSE 0 END ) AS Jun,
	SUM(CASE WHEN Month = 'Jul' THEN total ELSE 0 END ) AS Jul,
	SUM(CASE WHEN Month = 'Aug' THEN total ELSE 0 END ) AS Aug,
	SUM(CASE WHEN Month = 'Sep' THEN total ELSE 0 END ) AS Sep,
	SUM(CASE WHEN Month = 'Oct' THEN total ELSE 0 END ) AS Oct,
	SUM(CASE WHEN Month = 'Nov' THEN total ELSE 0 END ) AS Nov,
	SUM(CASE WHEN Month = 'Dec' THEN total ELSE 0 END ) AS Dis
	FROM tbl_ma GROUP BY element";
	$rs2 = mysql_query($sql2);
	$getRec2 = mysql_fetch_assoc($rs2);

Below is how print the data:

<?php 
while ($row = mysql_fetch_assoc($rs2)) {
?>
<tr>
<td style="color:black;background-color:#f5efef"><div align="left"><?php echo $row['element']; ?></div></td>
<?php if( $year != '2014' ){ ?>
<?php if( 1 <= $monthID ): ?><td><div align="center" style="color:black"><?php echo $row['Jan']; ?></div></td><?php endif; ?>
<?php if( 2 <= $monthID ): ?><td><div align="center" style="color:black"><?php echo $row['Feb']; ?></div></td><?php endif; ?>
<?php if( 3 <= $monthID ): ?><td><div align="center" style="color:black"><?php echo $row['Mac']; ?></div></td><?php endif; ?>
<?php if( 4 <= $monthID ): ?><td><div align="center" style="color:black"><?php echo $row['Apr']; ?></div></td><?php endif; ?>
<?php if( 5 <= $monthID ): ?><td><div align="center" style="color:black"><?php echo $row['May']; ?></div></td><?php endif; ?>
<?php if( 6 <= $monthID ): ?><td><div align="center" style="color:black"><?php echo $row['Jun']; ?></div></td><?php endif; ?>
<?php } ?>
<?php if( 7 <= $monthID ): ?><td><div align="center" style="color:black"><?php echo $row['Jul']; ?></div></td><?php endif; ?>
<?php if( 8 <= $monthID ): ?><td><div align="center" style="color:black"><?php echo $row['Aug']; ?></div></td><?php endif; ?>
<?php if( 9 <= $monthID ): ?><td><div align="center" style="color:black"><?php echo $row['Sep']; ?></div></td><?php endif; ?>
<?php if( 10 <= $monthID ): ?><td><div align="center" style="color:black"><?php echo $row['Oct']; ?></div></td><?php endif; ?>
<?php if( 11 <= $monthID ): ?><td><div align="center" style="color:black"><?php echo $row['Nov']; ?></div></td><?php endif; ?>
<?php if( 12 <= $monthID ): ?><td><div align="center" style="color:black"><?php echo $row['Dis']; ?></div></td><?php endif; ?>
<td><div align="center" style="color:black"><?php //echo average; ?></div></td>
</tr>                                  
<?php } ?>

 

 

[BuildMyWeb]

i cant understand what youre trying to do here.  but if you want to calculate an avg with php, why not something simple like

array_sum($values) / count($values)