Using MySQL results to do math

jonnyboy

Using PHP and MySQL, I want to pull two numbers out of the table and display them in an array, then I want to subtract one from the other and display the result as follows:

e.g.

Number 1 Number 2 New Field

100 097 -3
100 103 +3
100 107 +7

I want to show the minus figures in red and the plus figures in black. I am also not sure how to actually show the minus or plus signs.

Any help much appreciated.

Many thanks

Jon

TheIceman5

you can do all that with one query, you dont need arrays.

jonnyboy

Thanks for your reply, but can you please help me with the code as I am a bit of a newbie and have not found it in books so far.

Thanks

Jon

Ravenous

Stuff like this is not in a book. This is just simple logic.

Here's some pseudocode:

$var1 = num_from_db
$var2 = num2_from_db
$temp = $var1 - $var2
if( $temp < 0 )
        print temp in red
if( $temp >= 0 )
        print plus_sign
        print temp

Programming is all about logic and breaking down complex problems into smaller, simpler ones. You could have handled this.

jonnyboy

Thanks for your help, but I do not know enough to finish this although I am trying...

This is my array. I tried your suggestion in many different ways, but have struggled.

This is the best I have done so far. It gives me a calculated result, but I have not been able to show a figure with a leading+ if > than 0. The current calc displays with a leading - if it is < 0.

I also still would like to apply the colors of red for < and black for >.

echo "\n\n\t<td bgcolor=\"white\">" .
"<font color=\"red\">" .
$diff = $row["score"] - $row["par"] .
"</font></b></th>\n";

Any help appreciated.

Thanks

Jon

DeltaRho2K

You could do this something like:


$qry = "SELECT *, sum($number1-number2) AS Difference FROM table_name GROUP BY unique_field";
$result = mysql_query($qry);


while ($array = mysql_fetch_array($result)):

  If ($array['Difference'] >= '0'):
    $answer = "+".$array['Difference'];
  Else:
    $answer = "<font color=\"red\">".$array['Difference']."</font>";
  EndIf;


  echo $array['number1']." - ".$array['number2']." = ".$answer;

EndWhile;

This would be the "You can do it all with one query" method mentioned above.