Error coming up while running query on empty fields

Question

I'm building up that simple html form for inserting/retrieving data to/from mysql database. Just started up with two buttons: find and reset. Both of them are working fine BUT when I click FIND while fields are empty these errors coming up:

Warning: mysql_fetch_array() expects parameter 1 to be resource, boolean given in V:\u\miramo\Forum\xampp\htdocs\miramo_licensedb\myclass.php on line 76

Warning: mysql_free_result() expects parameter 1 to be resource, boolean given in V:\u\miramo\Forum\xampp\htdocs\miramo_licensedb\myclass.php on line 81

This is myclass.php piece:

    public function find() {

    $this->queryString = $this->makeQueryString();
    $this->errorMessages=$this->queryString;
    $query = mysql_query ($this->queryString);

    while($row=mysql_fetch_array($query)):
        $this->id= $row['id'];
        $this->name= $row['name'];
        $this->email = $row['email'];           
    endwhile; 
    mysql_free_result($query);

and myform.php:

 <?php
 include_once("./myclass.php");
 $my_class = new MyClass;


?>
<form action="myform.php" method="post">

<input type="text" value="<?php echo $my_class->id; ?>" name="id" class="" />
<input type="text" value="<?php echo $my_class->name; ?>" name="name" class="" />
<input type="text" value="<?php echo $my_class->email; ?>" name="email" class="" />


 <input type="submit" name="find" value="Find" />
 <input type="submit" name="reset" value="reset" />


  </form>

I tried to sort that out by adding

  if($result === FALSE){
  die(mysql_error());
  }

before my while loop but it didn't help. Was hoping that in case of running query on empty fields message "Insert values" will come up. Any suggestions??? Help highly appreciated

And thats the query:

    public function makeQueryString(){
    // build array of search terms
    $res= "SELECT id, name, email FROM test1 ";

// build array of search terms
 $i=0;


 if ($_POST['id'])
     $searchTermsArray[$i++] = "id LIKE '{$_POST['id']}'";
 if ($_POST['name'])
   $searchTermsArray[$i++] = "name LIKE '{$_POST['name']}'";
 if ($_POST['email'])
   $searchTermsArray[$i++] = "email LIKE '{$_POST['email']}'";

    // Construct query string from search terms array
 if ($i > 0 ) {
    $j=0;   
    $res .= " WHERE " . $searchTermsArray[0];

    for ($j=1; $j < $i; $j++)
        $res = $res . " AND " . $searchTermsArray[$j];
}
else
    $res= "";

 //Return query string
 return($res);
 }

Doesn't matter what the query is. The error says it all: You have an sql error, you failed to check for query failure, and blindly used the boolean "false" that was returned to indicate failure in further db operations, causing this error. — Marc B, May 08 '14 at 15:25
`Was hoping that in case of running query on empty fields message "Insert values" will come up`. So where's your attempt to do that? — Patrick Q, May 08 '14 at 15:26
Well I didn't echo anything yet because these errors were still coming up after adding if($result === FALSE){ die(mysql_error()); } — user2815059, May 08 '14 at 15:29
try adding `if($query === FALSE){ die(mysql_error()); }` before your while loop. `$result` is not initialized. — ebo, May 08 '14 at 15:30
When all of the fields are empty, you're ultimately running `mysql_query("");`. If you want it to behave the way you said, you need to add some code to check the returned value before injecting it into the call to `mysql_query()`. As a side note though, you really shouldn't be using the `mysql_*` functions at all. You should be using [mysqli](http://us1.php.net/manual/en/book.mysqli.php) or [PDO](http://us1.php.net/manual/en/book.pdo.php). — Patrick Q, May 08 '14 at 15:33
Why catch the error when you can prevent it in the first place? That's really no the best way to go. — Patrick Q, May 08 '14 at 15:36

score 1 · Accepted Answer · answered May 08 '14 at 15:39

The problem is that you're attempting to execute an empty query. Check for this case before executing your generated query (which may be empty);

public function find() {

$this->queryString = $this->makeQueryString();

if(empty($this->queryString))
{
    echo "Insert values";
    return;
}
else
{
    $this->errorMessages=$this->queryString;
    $query = mysql_query ($this->queryString);

    while($row=mysql_fetch_array($query)):
        $this->id= $row['id'];
        $this->name= $row['name'];
        $this->email = $row['email'];           
    endwhile; 
    mysql_free_result($query);
}

Error coming up while running query on empty fields

1 Answers1