PHP - Var = While Loop?--need Help With Best Method

 

My script has 3 classes (that are relevant to this discussion): DB, User and Validate. They are all in independent files and loaded automatically, when required, by an autoloader.
Both the User class and the Validate class have a private variable $_db which is instantiated by their class constructor: $this->_db = DB::getInstance();
At the top of the script I declare new instances: $user = new User(); and $validate = new Validate();
I then call a method in $user: $found = $user->findInUsers ( .... )
From within the findInUsers method I then want to call the query method in the DB class. My problem is that I can't find a way to do this that works.
I have tried $this->_db->query( ... ), $_db->query( ... ), but neither works.

The error messages I am getting a
An error occurred in script '/srv/http/classes/User.php' on line 42: Undefined variable $_db
Uncaught Error: Call to a member function query() on null in /srv/http/classes/User.php:42

Any pointers as to what I am doing wrong, or what I should be doing, would be most welcome.

Hey.   So the issue I'm having is consecutive loops on semi-large arrays, over and over. Consider this array:

$firstArray = array(
'row1' => array(
'dates' => array(
'2014-01-01' => array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3', 'key4' => 'value4', 'key5' => 'value5', 'key6' => 'value6', 'key7' => 'value7', 'key8' => 'value8', 'key9' => 'value9', 'key10' => 'value10'),
'2014-01-02' => array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3', 'key4' => 'value4', 'key5' => 'value5', 'key6' => 'value6', 'key7' => 'value7', 'key8' => 'value8', 'key9' => 'value9', 'key10' => 'value10'),
'2014-01-03' => array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3', 'key4' => 'value4', 'key5' => 'value5', 'key6' => 'value6', 'key7' => 'value7', 'key8' => 'value8', 'key9' => 'value9', 'key10' => 'value10'),
'2014-01-04' => array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3', 'key4' => 'value4', 'key5' => 'value5', 'key6' => 'value6', 'key7' => 'value7', 'key8' => 'value8', 'key9' => 'value9', 'key10' => 'value10'),
'2014-01-05' => array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3', 'key4' => 'value4', 'key5' => 'value5', 'key6' => 'value6', 'key7' => 'value7', 'key8' => 'value8', 'key9' => 'value9', 'key10' => 'value10'),
'2014-01-06' => array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3', 'key4' => 'value4', 'key5' => 'value5', 'key6' => 'value6', 'key7' => 'value7', 'key8' => 'value8', 'key9' => 'value9', 'key10' => 'value10'),
'2014-01-07' => array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3', 'key4' => 'value4', 'key5' => 'value5', 'key6' => 'value6', 'key7' => 'value7', 'key8' => 'value8', 'key9' => 'value9', 'key10' => 'value10'),
)
),
'row2' => array(
'dates' => array(
'2014-02-01' => array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3', 'key4' => 'value4', 'key5' => 'value5', 'key6' => 'value6', 'key7' => 'value7', 'key8' => 'value8', 'key9' => 'value9', 'key10' => 'value10'),
'2014-02-02' => array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3', 'key4' => 'value4', 'key5' => 'value5', 'key6' => 'value6', 'key7' => 'value7', 'key8' => 'value8', 'key9' => 'value9', 'key10' => 'value10'),
'2014-02-03' => array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3', 'key4' => 'value4', 'key5' => 'value5', 'key6' => 'value6', 'key7' => 'value7', 'key8' => 'value8', 'key9' => 'value9', 'key10' => 'value10'),
'2014-02-04' => array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3', 'key4' => 'value4', 'key5' => 'value5', 'key6' => 'value6', 'key7' => 'value7', 'key8' => 'value8', 'key9' => 'value9', 'key10' => 'value10'),
'2014-02-05' => array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3', 'key4' => 'value4', 'key5' => 'value5', 'key6' => 'value6', 'key7' => 'value7', 'key8' => 'value8', 'key9' => 'value9', 'key10' => 'value10'),
'2014-02-06' => array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3', 'key4' => 'value4', 'key5' => 'value5', 'key6' => 'value6', 'key7' => 'value7', 'key8' => 'value8', 'key9' => 'value9', 'key10' => 'value10'),
'2014-02-07' => array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3', 'key4' => 'value4', 'key5' => 'value5', 'key6' => 'value6', 'key7' => 'value7', 'key8' => 'value8', 'key9' => 'value9', 'key10' => 'value10'),
'2014-02-08' => array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3', 'key4' => 'value4', 'key5' => 'value5', 'key6' => 'value6', 'key7' => 'value7', 'key8' => 'value8', 'key9' => 'value9', 'key10' => 'value10'),
'2014-02-09' => array('key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3', 'key4' => 'value4', 'key5' => 'value5', 'key6' => 'value6', 'key7' => 'value7', 'key8' => 'value8', 'key9' => 'value9', 'key10' => 'value10'),
)
)
);

Originally the data comes from ~2-3 database tables, of course. But to ilustrate the point, this is how the main array looks like. This array usually contains anywhere between 10-50 rows, each row containing at least 10 dates, with 10 key/values each.   And after setting up all the data, it needs to be processed. Currently this is how a friend of mine did it..

$placeDataHere = array();
foreach($firstArray as $key => $dates) {
foreach($dates as $date => $values) {
foreach($values as $key => $value) {
$placeDataHere['DV_' . $date]['SM_' . $key] = 'KS_' . $value;
//Followed by another ~50-70 lines of processing the 3 loop's data..
...
...
....
....
....
....
....
....
}
}
}

Obviously this isn't good practise, but we can't seem to figure out a better way of doing it, since both the data and the loops are horribly nested.   This loop and setup of $firstArray is run anywhere between 10-20 times/request, due to amount of users we wish to process. So, the result is that this code can take up to over 2-3 minutes to complete, which isn't really optimal performance.   In short my question is, are there any better methods of handling this with the data setup we currently have?

Below is my output on the browser:

    Student: Kevin Smith (u0867587)
    Course: INFO101 - Bsc Information Communication Technology Course Mark 70 Grade
    Year: 3
   
   
    Module: CHI2550 - Modern Database Applications Module Mark: 41 Mark Percentage: 68 Grade: B
   
    Session: AAB Session Mark: 72 Session Weight Contribution 20%
   
    Session: AAE Session Mark: 67 Session Weight Contribution 40%


    Module: CHI2513 - Systems Strategy Module Mark: 31 Mark Percentage: 62 Grade: B
   
    Session: AAD Session Mark: 61 Session Weight Contribution 50%

Now where it says course mark above it says 70. This is incorrect as it should be 65 (The average between the module marks percentage should be 65 in the example above) but for some stange reason I can get the answer 65. I have a variable called $courseMark and that does the calculation. Now if the $courseMark is echo outside the where loop, then it will equal 65 but if it is put in while loop where I want the variable to be displayed, then it adds up to 70. Why does it do this.
   
    Below is the code:

Code: [Select]
    $sessionMark = 0;
    $sessionWeight = 0;
    $courseMark = 0;
   
    $output = "";
   
    $studentId = false;
    $courseId  = false;
    $moduleId  = false;
   
    while ($row = mysql_fetch_array($result))
    {
   
   
    $sessionMark += round($row['Mark'] / 100 * $row['SessionWeight']);
    $sessionWeight  += ($row['SessionWeight']);
        $courseMark = ($sessionMark /  $sessionWeight * 100);
   
          if($studentId != $row['StudentUsername'])
        {
   
            //Student has changed
            $studentId = $row['StudentUsername'];
   
            $output .= "<p><strong>Student:</strong> {$row['StudentForename']} {$row['StudentSurname']} ({$row['StudentUsername']})\n";
   
        }
             
        if($courseId != $row['CourseId'])
        {
   
            //Course has changed
            $courseId = $row['CourseId'];
   
            $output .= "<br><strong>Course:</strong> {$row['CourseId']} - {$row['CourseName']} <strong>Course Mark</strong>" round($courseMark) "<strong>Grade</strong>  <br><strong>Year:</strong> {$row['Year']}</p>\n";
   
        }
   
        if($moduleId != $row['ModuleId'])
        {
   
            //Module has changed
            if(isset($sessionsAry)) //Don't run function for first record
            {
   
                //Get output for last module and sessions
                $output .= outputModule($moduleId, $moduleName, $sessionsAry);
            }
   
            //Reset sessions data array and Set values for new module
   
            $sessionsAry = array();
            $moduleId    = $row['ModuleId'];
            $moduleName  = $row['ModuleName'];
        }
             
        //Add session data to array for current module
             
        $sessionsAry[] = array('SessionId'=>$row['SessionId'], 'Mark'=>$row['Mark'], 'SessionWeight'=>$row['SessionWeight']);
             
    }    //Get output for last module
   
    $output .= outputModule($moduleId, $moduleName, $sessionsAry);
   
    //Display the output
    echo $output;
I think the problem is that it is outputting the answer of the calculation only for the first session mark. How in the while loop can I do it so it doesn't display it for the first mark only but for all the session marks so that it ends up showing the correct answer 65 and not 72?

Hey guys,

Got another question im hoping someone can help me with.

I have a foreach loop (for use in a mysql query):

   foreach ($interests as $interest) {
       $query .= "($id, $interest), ";
   }

problem is i do not want the comma(,) in the last loop.

Is there some kinda of function i can use so it does not insert it on last loop?

Or should i just use a for loop with a nested if loop? something like ;

   for($i=0; $i < count($interests); $i++){
      $query .=
      "($id, '$interests[$i]')";
      if($i + 1 < count($interests)) {
         $query .= ", ";
      }
      }


Cheers guys

I am working to echo the results in a while or for loop... Both of my sample codes work, but the results are wrong!

The while loop ONLY echos a result IF the first record in the postings table matches the id passed (does not display a result unless the first record has a match)

The if loop displays ALL listings with the same name (counts them all) so there are no unique listings!


<?php

$posts_by_city_sql = "SELECT * FROM postings WHERE id='$_GET[id]'";
$posts_by_city_results = (mysqli_query($cxn, $posts_by_city_sql)) or die("Was not able to grab the Postings!");

/* While Loop  */
while($posts_by_city_row = mysqli_fetch_array($posts_by_city_results)) {
echo "<li><a href='posting_details.php?id=$posts_by_city_row[id]'>$posts_by_city_row[title]</a></li>";
}

/* For Loop  */
$posts_by_city_row = mysqli_fetch_array($posts_by_city_results);
 
for ($i=0; $i<sizeof($posts_by_city_row); $i++) {
echo "<li><a href='posting_details.php?id=$posts_by_city_row[id]'>$posts_by_city_row[title]</a></li>";
 }

?>

Results with for loop (there are 7 total unique book names, but it's just counting the first match on id 7 times like below):

AJAX for Beginners
AJAX for Beginners
AJAX for Beginners
AJAX for Beginners
AJAX for Beginners
AJAX for Beginners
AJAX for Beginners
AJAX for Beginners