How does php solve the problem of not uploading files larger than 8M

Development of a file upload sharing website, once wanted to use the following code to achieve the function of file upload:

 
<form enctype="multipart/form-data" action="add_file.php" method="post"> 
<fieldset><legend>Fill out the form to upload a file:</legend> 
<?php // Create the inputs. 
for ($i = 0; $i < $counter; $i++) { 
echo '<b>File:</b> <input type="file" name="upload' . $i . '" /> 

<b>Description:</b> <textarea name="description' . $i . '" cols="40" rows="5"></textarea> 


'; 
} 
?> 
</fieldset> 
<input type="hidden" name="submitted" value="TRUE" /> 
[align=center]<input type="submit" name="submit" value="Submit" />[/align] 
</form> 

File couldn't be moved when uploading a slightly larger file is found during actual execution.
The database shows the name of the file, not the size.
When a file larger than 8M is uploaded, the page does not respond at all.