How to remove the fatal error when fetching an assoc array

Question 1

I am receiving a fatal error in my php/mysqli code which states that on line 46:

Fatal error: Call to undefined method mysqli_stmt::fetch_assoc() in ...

I just want to know how can I remove this fatal error?

The line of code it is pointing at is here:

$row = $stmt->fetch_assoc();

ORIGINAL CODE:

$query = "SELECT Username, Email FROM User WHERE User = ?";
// prepare query
$stmt=$mysqli->prepare($query);
// You only need to call bind_param once
$stmt->bind_param("s",$user);
// execute query
$stmt->execute(); 
// get result and assign variables (prefix with db)
$stmt->bind_result($dbUser, $dbEmail);
//get number of rows
$stmt->store_result();
$numrows = $stmt->num_rows();                                      

if ($numrows == 1){

$row = $stmt->fetch_assoc();
$dbemail = $row['Email'];

}

UPDATED CODE:

$query = "SELECT Username, Email FROM User WHERE User = ?";
// prepare query
$stmt=$mysqli->prepare($query);
// You only need to call bind_param once
$stmt->bind_param("s",$user);
// execute query
$stmt->execute(); 
// get result and assign variables (prefix with db)
$stmt->bind_result($dbUser, $dbEmail);
//get number of rows
$stmt->store_result();
$numrows = $stmt->num_rows();                                      

if ($numrows == 1){    
  $row = $stmt->fetch_assoc();
  $dbemail = $row['Email'];    
}

Question 2

The variable $stmt is of type mysqli_stmt, not mysqli_result. The mysqli_stmt class doesn't have a method "fetch_assoc()" defined for it.

You can get a mysqli_result object from your mysqli_stmt object by calling its get_result() method. For this you need the mysqlInd driver installed!

$result = $stmt->get_result();
row = $result->fetch_assoc();

If you don't have the driver installed you can fetch your results like this:

$stmt->bind_result($dbUser, $dbEmail);
while ($stmt->fetch()) {
    printf("%s %sn", $dbUser, $dbEmail);
}

So your code should become:

$query = "SELECT Username, Email FROM User WHERE User = ?";
// prepare query
$stmt=$mysqli->prepare($query);
// You only need to call bind_param once
$stmt->bind_param("s",$user);
// execute query
$stmt->execute(); 
// bind variables to result
$stmt->bind_result($dbUser, $dbEmail);
//fetch the first result row, this pumps the result values in the bound variables
if($stmt->fetch()){
    echo 'result is ' . dbEmail;
}

Question 3

I went ahead and ran a test where one query uses a prepared statement, and the other builds the entire query then executes that. I'm probably not making what I'm wanting to know easy to understand.

Here's my test code. I was thinking prepared statements sort of held back execution until a $stmt->close() was called to optimize it or something. That doesn't appear to be the case though as the test that builds the query using real_escape_string is at least 10 times faster.

<?php

$db = new mysqli('localhost', 'user', 'pass', 'test');

$start = microtime(true);
$a = 'a';
$b = 'b';

$sql = $db->prepare('INSERT INTO multi (a,b) VALUES(?, ?)');
$sql->bind_param('ss', $a, $b);
for($i = 0; $i < 10000; $i++)
{
    $a = chr($i % 1);
    $b = chr($i % 2);
    $sql->execute();
}
$sql->close();

echo microtime(true) - $start;

$db->close();

?>

Question 4

This actually depends on the Mysql server. The default max size for all data combined in the entire query is 1mb. See: http://dev.mysql.com/doc/refman/5.1/en/packet-too-large.html

If your data combined is under that "max_allowed_packet" threshold, just use "s" for the binding type for any text field. Infact, you can usually get away with using "s" for any field type at all (date, float, etc).

If your entire entry combined that you want to insert is over 1mb (or whatever you reset it to) in length, you'll want to use mysqli_stmt::send_long_data method and the "b" binding type to send this particular field in chunks.

Question 5

One of the first things that np.save does is

arr = np.asanyarray(arr)

So yes it is trying to turn your list into an array.

Constructing an object array from arbitrary sized arrays or lists is tricky. np.array(...) tries to create as high a dimensional array as it can, even attempting to concatenate the inputs if possible. The surest way is to do what you did - make the empty array and fill it.

A slightly more compact way of constructing the object array:

In [21]: alist = [np.zeros((2, 2)), np.zeros((2,3))]
In [22]: arr = np.empty(len(alist), dtype=object)
In [23]: arr[:] = alist
In [24]: arr
Out[24]: 
array([array([[ 0.,  0.],
       [ 0.,  0.]]),
       array([[ 0.,  0.,  0.],
       [ 0.,  0.,  0.]])], dtype=object)

Here are 3 scenarios:

Arrays that match in shape, combine into a 3d array:

In [27]: np.array([np.zeros((2, 2)), np.zeros((2,2))])
Out[27]: 
array([[[ 0.,  0.],
        [ 0.,  0.]],

       [[ 0.,  0.],
        [ 0.,  0.]]])
In [28]: _.shape
Out[28]: (2, 2, 2)

Arrays that don't match on the first dimension - create object array

In [29]: np.array([np.zeros((2, 2)), np.zeros((3,2))])
Out[29]: 
array([array([[ 0.,  0.],
       [ 0.,  0.]]),
       array([[ 0.,  0.],
       [ 0.,  0.],
       [ 0.,  0.]])], dtype=object)
In [30]: _.shape
Out[30]: (2,)

And awkward intermediate case (which may even be described as a bug). The first dimensions match, but the second ones don't):

In [31]: np.array([np.zeros((2, 2)), np.zeros((2,3))])
...
ValueError: could not broadcast input array from shape (2,2) into shape (2)
       [ 0.,  0.]])], dtype=object)

It's as though it initialized a (2,2,2) array, and then found that the (2,3) wouldn't fit. And the current logic doesn't allow it to backup and create the object array as it did in the previous scenario.

If you wanted to put the two (2,2) arrays in object array you'd have to use the create and fill logic.

Question 6

Because you can not catch the exception which is happening at Application.Exit(), this sounds like you are facing a bug I've seen before. Please try to comment out all the lines where you set the Font attribute. If the application exists without the error message, you are facing a bug which affects NetCF 3.5 at WinCE 6.0 only. See this link for more information.

How to remove the fatal error when fetching an assoc array

Answers

php,mysqli