Question

I Have two tables

Table1 is

    idno         marks
     1             12
     1             13
     1             22 
     2             32 
     2             35
     2             11  and so on

Table2 is

    idno          marks
     1              16
     1              22 
     1              21 
     2              35 
     2              16
     2              22   and so on

I am providing a form for user to enter the idno and submit

If user enters “1” in form and submit then the output should be

        Total Marks
            106 

i.e the sum of all marks of Idno 1 in Table1 + sum of all marks of Idno 1 in table2

(12+13+22)+(16+22+21) = 106

and i am using the following code

<form id="form" action="sum.php" method="post">
<td><p align="center"> IDNO : <input type="text" name="id" id="id" maxlength="10"></p></td>
<input type="submit" id="submit" class='btnExample' value="Click here to get your Result"
</form>

<?PHP
$user_name = "admin";
$password = "123456";
$database = "demo";
$server = "localhost";
$db_handle = mysql_connect($server, $user_name, $password);
$db_found = mysql_select_db($database, $db_handle);

if ($db_found) {
$id = mysql_real_escape_string($_POST['id']);
$add = "SELECT htno, SUM(tech) 
FROM(SELECT htno, SUM(tm) AS tech FROM jbit WHERE htno='$id'
UNION ALL  
SELECT htno, SUM(tm1) AS tech  FROM hmm WHERE htno='$id') AS tech4 "; 
$result3 = mysql_query($add);
echo "
<center><table id='mytable' cellspacing='0'  border=3 align=center>
<tr>
<TH scope='col'>Total Marks</TH>
</tr><center>";
while ($row1 = mysql_fetch_assoc($result3)){
echo "<tr>";
echo "<td align=center>" . $row1['tech4']. "</td>";
echo "</tr>";
}
mysql_close($db_handle);
else {
print "Database NOT Found ";
mysql_close($db_handle);
}

but output is blank

please help me out

Answer 1

You seem to be missing GROUP by htno in both parts of the union after WHERE clauses. Or you may consider removing htno field from SELECT clauses of the union.

 select sum(sm) from
   (select Sum(marks) sm from sums1 where idno=1
   union
   select Sum(marks) sm from sums2 where idno=1 ) ss

Tested this on mysql and it works