使用foreach（）创建表

I have following PHP code contain 2 foreachs

echo "<table class='table table-bordered'>";
foreach($resultOld as $key=>$value)
{
    foreach ($value as $key1 => $subjects) {
        $checked = $subjects;
        echo  "<tr><tr class=\"".$subjects."\">$key1
            <input type='checkbox' class=\"".$subjects."\"  value='checked' name=\"".$key1."JAN\" $checked/> </tr>               
           </tr>" ;
    }
}
echo "</table>";

$resultOld is a fetchAll(PDO::FETCH_ASSOC) output and it contains a two dimensional array. $subjects will return 661 words from the database which means the $resultOld array have 661 elements. And after every 12 cells I want to start a new line (tr). That means I need 55 rows in the table. How to achieve this using PHP?

If you want a new row after every 12 records, you need to use a counter and check the count -

$counter = 1;
echo "<table class='table table-bordered'>";
echo "<tr>"; //start the first row
foreach($resultOld as $key=>$value)
{
    foreach ($value as $key1 => $subjects) {

        // if the 13th cell, end last row, and start new row
        if ($counter%12==1){
                      echo "</tr><tr>";}
        $checked = $subjects;
        echo  "<td class=\"".$subjects."\">$key1
            <input type='checkbox' class=\"".$subjects."\"  value='checked' name=\"".$key1."JAN\" $checked/> </td>" ;

        // increase counter
        $counter++;
    }
}
echo "</tr>"; // end last row
echo "</table>";

First, note that your HTML structure is wrong. I recommend thinking about this is a little more steps. Perhaps layout a single row <table> HTML structure for reference between slicing it up into PHP

Here's an example:

<table class="...">
<tbody> <!-- I recommend using the tbody tag -->
    <tr>
        <td>...</td>
    </tr>
</tbody>
</table>

There's three basic things to think about:

1. The Table Body
2. The Row
3. The Columns (ie. Cells)

Step 1 is to print the table body. You're doing fine here:

echo '<table class="table table-bordered">';
echo '<tbody>';
//...
<echo '</tbody>';
echo '</table>';

Step 2 is to loop through your rows

echo '<table class="table table-bordered">';
echo '<tbody>';

// Loop Through Rows
foreach($resultOld as $key=>$value)
{
    echo '<tr>'; // start a new row
    // ...
    echo '</tr>'; // end a row
}

<echo '</tbody>';
echo '</table>';

Step 3 is to loop through each column or cell of the table:

// STEP 1
echo '<table class="table table-bordered">';
echo '<tbody>';

// STEP 2
// Loop Through Rows
foreach($resultOld as $key=>$value)
{
    echo '<tr>'; // start a new row

    // STEP 3
    foreach ($value as $key1 => $subjects) {
        $checked = $subjects;
        // Start a new column/cell
        echo '<td class="' . $subjects . '">';

        // Print cell contents
        echo $key1;
        echo '<input type="checkbox" class="' . $subjects . '" value="checked" name="' . $key1 . 'JAN" '. $checked . '/>';

        // End column/cell
        echo '</td>';
    } // END STEP 3

    echo '</tr>'; // end a row
} // END STEP 2

echo '</tbody>';
echo '</table>';
 // END STEP 1

Some notes on your code:

• You're printing 2 Table rows instead of printing a table row and a table column (ie: <tr><tr> instead of <tr><td>;
• You need to print the row inside the first loop, not the second loop.
• The second, nested, loop prints out your 2nd dimension or columns.

For me, I like to use single quotes (') with printing HTML. I do this because I use double quotes (") for HTML attributes. This allows me to avoid having to escape the double quote character and getting a hard to read '\""' situation, which can cause simple syntax bugs.

Also when running into problems printing HTML, braking the HTML into multiple echo/print statements can help you structure your code and troubleshoot the problems. Once it's working you can go back and refactor them into a single echo statement, however the performance difference would probably so minor that it's not worth the time.

I hope that helps!