calculations on specific rows in table of database using php - php

Question

i'm working on a php project that manages teachers in school. but i'm stuck with a problem, i have two tables in my database, first one T1 has on row, second T2 has multiple rows, but they have the same columns number. in a third table T3 i need to fill a column with the total of
(cell1 of T1*cell1 of T2) + (cell2 of T1*cell2 of T2)+ (cell3 of T1*cell3 of T2)....to the last column
i just couldn't find the right way to do this
this is the part that shows the tables from my db
<?php
$host="localhost";
$user="root";
$pass="";
$bdd="test";
$cnx=mysql_connect($host,$user,$pass);
if(!$cnx)
echo"connexion echouee"."</br>";
else
echo"connexion reussie"."</br>";
if (mysql_select_db($bdd))
echo"base de donnees trouvee"."</br>";
else
echo"base de donnees introuvable"."</br>";
$req1="SELECT * FROM `table1`";
$res1=mysql_query("$req1");
// printing table rows
while($row1 = mysql_fetch_row($res1))
{
echo "<tr>";
foreach($row1 as $cell1)
echo "<td>|$cell1|</td>";
echo "</tr>"; echo"</br>";
}
echo "_____</br>";
$req2="SELECT * FROM `table2`";
$res2=mysql_query("$req2");
// printing table rows
while($row2 = mysql_fetch_row($res2))
{
echo "<tr>";
foreach($row2 as $cell2)
echo "<td>|$cell2|</td>";
echo "</tr>";echo"</br>";
}
?>

Answer 1

As long as it is guaranteed that table1 will return 1 row, here is a suggestion:
Instead of using a while loop to fetch the contents, just fetch the row, so the contents of table1 are in $row1
Change foreach($row2 as $cell2) to a foreach($row2 as $key=>$value) format. This way you will have the index of the corresponding element in $row1
Inside the foreach($row2 as $key=>$value) loop, use an accumulator to calculate "Column I". E.G. $tot += $value * $row1[$key]
"echo" the accumulater column before the </tr>
You also probably want to add an empty <td> in the $row1 loop to make sure that all the rows have the same number of columns.

Answer 2

You can traverse second table and calculate total with nested loop:
$res1 = mysql_query("SELECT * FROM `table1`");
$res2 = mysql_query("SELECT * FROM `table2`");
$row1 = mysql_fetch_row($res1);
$row = 0;
// for each row of second table
while ($row2 = mysql_fetch_row($res2)) {
$row++;
$total = 0;
// for each column of first table's row
foreach ($row1 as $index => $table1RowValue) {
// get value of same column in the second table's row
$table2RowValue = $row2[$index];
// calculate aggregated value
$total += $table1RowValue * $table2RowValue;
}
// print result
echo "Line $row: $total</br>";
}