PHP - put the student name and grade into suitable skill name - php

Question

(1) class
(2) studentmark
(3) skill
PHP code:
<?php
//DB CONNECTION
//---(1)Get skillname---
$q = "SELECT skillName FROM skill ORDER BY skillName asc";
$r = mysqli_query($dbc, $q);
$num_rows = mysqli_num_rows($r);
while($row = mysqli_fetch_array($r, MYSQLI_ASSOC))
{
$skills[] = $row['skillName'];
}
//---(2)Get classname---
$q1 = "SELECT className FROM class";
$r1 = mysqli_query($dbc, $q1);
$num_rows1 = mysqli_num_rows($r1);
while($row1 = mysqli_fetch_array($r1, MYSQLI_ASSOC))
{
$className[] = $row1['className'];
}
//---(3)Create table---
echo '<table border="1" style="border-collapse: collapse; text-align: center">';
echo '<tr>';
for($a = 0; $a < $num_rows; $a++)
{
echo '<th colspan="2">'.$skillName[$a].'</th>';
}
echo '</tr>';
for($b = 0; $b < $num_rows; $b++)
{
echo '<th>Student Name</th>';
echo '<th>Grade</th>';
}
echo '</tr>';
//---(4)Get student name and grade---
for($s = 0; $c < $num_rows1; $c++)
{
$q2 = "SELECT GROUP_CONCAT(sm.studentName) as studentName,
GROUP_CONCAT(sm.studentGrade) as studentGrade,
s.skillName
FROM studentmark sm
LEFT JOIN skill s ON sm.skillID = s.skillID
WHERE sm.className = '".$className[$c]."'
GROUP BY s.skillID";
$r2 = mysqli_query($dbc, $q2);
$num_rows2 = mysqli_num_rows($r2);
$value = array();
while($row2 = mysqli_fetch_array($r2, MYSQLI_ASSOC))
{
$value[] = $row2;
}
echo '<tr>';
for($d = 0; $d < $num_rows2; $d++)
{
echo '<td>'.$value[$d]['studentName'].'</td>';
echo '<td>'.$value[$d]['studentGrade'].'</td>';
}
echo '</tr>';
}
echo '</table>';
?>
From above code, my output is below:
I am almost finished. I can show the student name and grade in 1 row.
Now, the last thing I want to do is put them into suitable skill name like below:
I want to compare the $skills and s.skillname on $q2.
Below is my logic:
if($value[X]['skillName'] == $skills[X])
{
//put student name and grade inside
}
else
{
//empty cell
}
But I don't know where should I open for loop and put my logic in (4). Can someone help me?

Answer 1

So I'm definitely messing up your nice clean code for the sake of not looping through the data multiple times. I also display the classnames cause that seems like useful info.
I changed some variable names cause I found it easier to remember what each variable was for. Also, note how the student info query is only executed once. Normaly (read: I can't think of a reason why you wouldn't but I'm CMA), you want to minimize the number of times you query the database
The code below will replace the entire script you posted.
<?php
//DB CONNECTION
$dbc = // magic connection sauce you already have
// get skills and stash how many there are
$q_class = "SELECT skillName FROM skill ORDER BY skillName asc";
$r_class = mysqli_query($dbc, $q_class);
$num_skills = mysqli_num_rows($r_class);
// start table code so that we can echo the skillname headers
echo '
<table border="1" style="border-collapse: collapse; text-align: center">
<thead>
<tr>
<th rowspan=2>Classes</th>';//header for class name column
$header = array();
while($row = mysqli_fetch_array($r_class, MYSQLI_ASSOC))
{
$skills[] = $row['skillName'];
// store both thead rows at the same time so that we can echo them out properly later
$header['first'][] = '
<th colspan="2">' . $row['skillName'] . '</th>';
$header['second'][] = '
<th>Student Name</th>
<th>Grade</th>';
}
echo '
' . implode($header['first']) . '
</tr>
<tr>' . implode($header['second']) . '
</tr>';
// clean-up
mysqli_free_result($r_class);
// get class names and stash how many there are
$classes = array();
$query_class = "SELECT className FROM class";
$r_class = mysqli_query($dbc, $query_class);
$num_classes = mysqli_num_rows($r_class);
while($row = mysqli_fetch_array($r_class, MYSQLI_ASSOC))
{
$classes[] = $row['className'];
}
// clean-up
mysqli_free_result($r_class);
echo '
</thead>
<tbody>';
// pull query out of loop so that you'll only have to execute it once.
$studentInfoQuery = "
SELECT
GROUP_CONCAT(sm.studentName) as studentName,
GROUP_CONCAT(sm.studentGrade) as studentGrade,
s.skillName,
sm.className
FROM studentmark sm
LEFT JOIN skill s ON sm.skillID = s.skillID
GROUP BY sm.className,s.skillID";
$r_students = mysqli_query($dbc,$studentInfoQuery);
$num_studentRows = mysqli_num_rows($r_students);
$studentRows = array();
while($row = mysqli_fetch_array($r_students, MYSQLI_ASSOC)) {
// with our query, we only find 1 cell-pair per skill per class
$studentRows[$row['skillName']][$row['className']] = '
<td>' . $row['studentName'] . '</td>
<td>' . $row['studentGrade'] . '</td>';
}
// everybody do their share! // actually, more clean-up
mysqli_free_result($r_students);
for($j = 0; $j < $num_classes; $j++) {
echo "
<tr>
<th>" . $classes[$j] . "</th>";
for($i = 0; $i < $num_skills; $i++) {
// always echo out a cell, even if we have student info for it
// example: if(isset($studentRows['Listening']['1A'])) echo it out else echo cell
if(isset($studentRows[$skills[$i]][$classes[$j]]))
echo $studentRows[$skills[$i]][$classes[$j]];
else
echo "
<td colspan=2>No skill-class-student value</td>";
}
echo "
</tr>";
}
echo '
</tbody>
</table>';
?>
Results:

Answer 2

You are doing fine(although the things can be optimized) up to the last loop of step 4 in your design.
The problem you face right there is that you have a set of results which represent each class in it's rows. Now you need to spread them out in to skill table, importantly, without leaving vertical gaps.
The solution is to do it in a two dimension array in the memory and then create the table from it - because each cell in the memory is easily addressable than cells in an html table.
Memory table is going to be something like this:
|Skill 1 | Skill 2 | Skill3|
|stdnt 1 |stdnt 2,3|stdnt 4|
| | |stdnt 5|
Please note how I have used array_search to get the index of a particular skill and use it in array_push to insert the student in to the correct child array. Then I have just translated it in to an HTML table
I'm replacing your last loop with the following code:
//This is our memory table. Let's create it and add number of child arrays
//equal to number of skills.
$memTable = array();
for ($i = 0; $i <= sizeOf($skills) - 1; $i++) {
$memTable[$i] = array();
}
//Lets spread out your student information in to this 2d array now
foreach ($value as $student) {
//Get the index of the skill
$skillIndex = array_search($student['skillName'], $skills);
//Now go to appropriate child array and insert your student there
array_push($memTable[$skillIndex], $student);
};
//Lets create the table now
$emptyCount = 0;
$currentRow = 0;
//Do until all the skill arrays are empty for a row
while ($emptyCount < 3) {
echo "<tr>";
$emptyCount = 0;
foreach ($memTable as $skillLevel) {
if (sizeof($skillLevel) - 1 < $currentRow) {
$emptyCount ++;
echo "<td>&nbsp</td>";
echo "<td>&nbsp</td>";
}
else {
echo "<td>" . $skillLevel[$currentRow]['studentGrade'] . "</td>";
echo "<td>" . $skillLevel[$currentRow]['studentGrade'] . "</td>";
}
}
$currentRow++;
echo "</tr>";
};
Please note that the skills will be rendered in the table according to the order they are in the $skills array. Please ask me questions if there is any place that is not clear to you. You might need to adjust some String names to adopt in to your code.
UPDATE
while ($emptyCount < sizeof($skills)) is more accurate.