二维数组作为对象名?

Dynamically created textbox would have names in array format.

<input type="textbox" id="textbox[]" name="textbox[]">

If updating dynamically created check box would be:

<input type="checkbox" id="chkbox[]" name="chkbox[]">

$checkbox = $_POST['chkbox'];
$id = "('" . implode( "','", $checkbox ) . "');" ;
$sql = "UPDATE [table] SET [col] = [value] WHERE id IN " . $id . ";

How could I do the same idea with text boxes?

Since you have an UPDATE statement in your question I assume you're sending existing records from your database (having some kind of id) to the client first.
In that case you can put that id in the field name, e.g.

<input type="text" name="text[47] value="..." />
<input type="text" name="text[74] value="..." />
<input type="text" name="text[39] value="..." />

and then on the server side iterate the data like

foreach( $_POST['text'] as $id=>$value ) {
  // your database action here, preferably a prepared statement
}

something to play with:

<html>
    <head>
        <title>...</title>
        <style type="text/css">
            span.editbtn { cursor: pointer; }
        </style>

    </head>
    <body>
        <form method="POST" action="test.php">
            <!-- something like this your script would produce from the SELECT query -->
            <fieldset class="editgroup"><input type="text"  name="post[47]" value="value for id 47" disabled /></fieldset>
            <fieldset class="editgroup"><input type="text"  name="post[74]" value="value for id 74" disabled /></fieldset>
            <fieldset class="editgroup"><input type="text"  name="post[89]" value="value for id 89" disabled /></fieldset>
            <fieldset class="editgroup"><input type="text"  name="post[31]" value="value for id 31" disabled /></fieldset>
            <input type="submit" />
        </form>
        <div id="foo">.</div>
        <script src="https://ajax.googleapis.com/ajax/libs/jquery/2.2.0/jquery.min.js"></script>
        <script>
            $(document).ready(function() {
                $('fieldset.editgroup').each(function() {
                    $(this).append('<span class="editbtn">&#x270e;</span>');
                });
                $('fieldset.editgroup').on('click', '.editbtn', function() {
                    $(this).siblings('input').prop('disabled', false);
                });
            }); 
        </script>
    </body>
</html>

check the result in test.php via <pre><?php var_export($_POST); ?></pre>