mysql_fetch_array()

[Irksome]

Hi all.

 

I've just started to make my own forum as a hobby, but have ran into this problem:

 

Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in /home/public_html/forum/viewthread.php on line 45

 

This shows up whenever I try to view a thread.

 

The code for the page is as follows:

 

<?php

require '../db.php';

$tbl_name="comforum_threads"; // Table name

// get value of id that sent from address bar
$id=$_GET['id'];

$sql="SELECT * FROM $tbl_name WHERE id='$id'";
$result=mysql_query($sql);

$rows=mysql_fetch_array($result);
?>
<table width="100%" border="1" cellspacing="0" cellpadding="0">
  <tr>
    <td width="93%"><? echo $rows['datetime']; ?></td>
    <td width="7%"> </td>
  </tr>
</table>
<table width="100%" border="1" cellspacing="0" cellpadding="0">
  <tr>
    <td width="8" valign="top"><? echo $rows['name']; ?></td>
    <td width="83%" valign="top"><p><? echo $rows['thread']; ?><hr></p>
      <p><? echo $rows['detail']; ?></p>
      </td>
  </tr>
</table>

<?php
$tbl_name2="comforum_posts"; // Switch to table "comforum_posts"

$sql2="SELECT * FROM $tbl_name2 WHERE question_id='$id'";
$result2=mysql_query($sql2);

while($rows=mysql_fetch_array($result2)){
?>

<table width="100%" border="1" cellspacing="0" cellpadding="0">
  <tr> 
    <td width="82%"><? echo $rows['a_datetime']; ?></td>
    <td width="18%"><? echo $rows['a_id']; ?></td>
  </tr>
</table>
<table width="100%" border="1" cellspacing="0" cellpadding="0">
  <tr> 
    <td width="8" valign="top"><? echo $rows['a_name']; ?> </td>
    <td width="83%" valign="top"><p><? echo $rows['thread']; ?><hr></p>
      <p><? echo $rows['a_answer']; ?></p></td>
  </tr>
</table>

<?
}

$sql3="SELECT view FROM $tbl_name WHERE id='$id'";
$result3=mysql_query($sql3);

$rows=mysql_fetch_array($result3);
$view=$rows['view'];

// if have no counter value set counter = 1
if(empty($view)){
$view=1;
$sql4="INSERT INTO $tbl_name(view) VALUES('$view') WHERE id='$id'";
$result4=mysql_query($sql4);
}

// count more value
$addview=$view+1;
$sql5="update $tbl_name set view='$addview' WHERE id='$id'";
$result5=mysql_query($sql5);

mysql_close();
?>

<table width="100%" border="1" cellspacing="0" cellpadding="0">
  <tr>
    <td><p>Quick Reply</p></td>
  </tr>
</table>
<table width="100%" border="1" cellspacing="0" cellpadding="0">
  <tr>
    <td><table width="100%" border="0" align="center" cellpadding="0" cellspacing="1" bgcolor="#CCCCCC">
<tr>
<form name="form1" method="post" action="postprocess.php">
<td>
<table width="100%" border="0" cellpadding="3" cellspacing="1" bgcolor="#FFFFFF">
<tr>
<td width="11%"><strong>Name</strong></td>
<td width="83%"><input name="a_name" type="text" id="a_name" size="45"></td>
</tr>
<tr>
<td><strong>Email</strong></td>
<td><input name="a_email" type="text" id="a_email" size="45"></td>
</tr>
<tr>
                  <td valign="top"><strong>Message</strong></td>
<td><textarea name="a_answer" cols="45" rows="3" id="a_answer"></textarea></td>
</tr>
<tr>
<td> </td>
<td><input name="id" type="hidden" value="<? echo $id; ?>"></td>
</tr>
<tr>
<td> </td>
<td width="6%"><input type="submit" name="Submit" value="Submit"> <input type="reset" name="Submit2" value="Reset"></td>
</tr>
</table>
</td>
</form>
</tr>
</table></td>
  </tr>
</table>
<p> </p>
<table width="100%" border="1" cellspacing="0" cellpadding="0">
  <tr>

  </tr>
</table>

 

I also have another error when replying to a thread:

 

Warning: mysql_fetch_array(): supplied argument is not a valid MySQL result resource in /home/public_html/forum/postprocess.php on line 15

ERROR

 

The code for that page is:

 

<?php

require '../db.php';

$tbl_name="comforum_posts"; // Table name

// Get value of id that sent from hidden field
$id=$_POST['id'];

// Find highest answer number.
$sql="SELECT MAX(a_id) AS Maxa_id FROM $tbl_name WHERE question_id='$id'";
$result=mysql_query($sql);
$rows=mysql_fetch_array($result);

// add + 1 to highest answer number and keep it in variable name "$Max_id". if there no answer yet set it = 1
if ($rows) {
$Max_id = $rows['Maxa_id']+1;
}
else {
$Max_id = 1;
}

// get values that sent from form
$a_name=$_POST['a_name'];
$a_email=$_POST['a_email'];
$a_answer=$_POST['a_answer'];

$datetime=date("d/m/y H:i:s"); // create date and time

// Insert answer
$sql2="INSERT INTO $tbl_name(question_id, a_id, a_name, a_email, a_answer, a_datetime)VALUES('$id', '$Max_id', '$a_name', '$a_email', '$a_answer', '$datetime')";
$result2=mysql_query($sql2);

if($result2){
echo "Successful<BR>";
echo "<a href='viewthread.php?id=".$id."'>View your answer</a>";

// If added new answer, add value +1 in reply column
$tbl_name2="forum_question";
$sql3="UPDATE $tbl_name2 SET reply='$Max_id' WHERE id='$id'";
$result3=mysql_query($sql3);

}
else {
echo "ERROR";
}

mysql_close();
?>

 

I have no idea why it's doing it. Could anyone shed any light on this subject?

 

Thanks.

[piznac]

Im not sure where the error is coming from. But I would suggest everytime you run a "mysql_query" you also and "mysql_query($yourquery) or die ("this query error" . mysql_error())" or something like that to let you know if your queries are running fine. There could be a problem with your queries. It might not be that, but I feel its an very good practice.

[trq]

You never check your query actually succeeds before trying to use its results. The general syntax for a SELECT statement should always be something like....

 

<?php

  // connect to db.
  if ($result = mysql_query($sql)) {
    // its now confirmed that $result holds a valid resource.
    if (mysql_num_rows($result)) {
      // its now confirmed that $result holds a resource which actually contains data.
      $row = mysql_fetch_assoc($result);
    } else {
      // no data found.
    }
  } else {
   // query failed. good place to debug eg;
   echo mysql_error() . "<br />$sql";
  }

?>