So, let's say you have a table with four text fields - fieldOne, fieldTwo, fieldThree, fieldFour.
Your html form should look like this (i'm skipping irrelevant parts).
<form method="POST">
<textarea name='data[fieldOne]'></textarea>
<textarea name='data[fieldTwo]'></textarea>
<textarea name='data[fieldThree]'></textarea>
<textarea name='data[fieldFour]'></textarea>
</form>
Now, your PHP code:
$data = $_POST['data']; // PHP converts names like data[fieldOne] into arrays.
foreach ($data as $key => $value) {
$fieldNames[] = "`{$key}`"; //field names for our insert statement - `fieldOne`, `fieldTwo`, etc...
$values[":{$key}"] = strip_tags($value);
}
$stmt = $pdo->prepare("INSERT INTO `tableName` (".implode(', ', $fieldNames).") VALUES (".implode(", ", array_keys($values)).")"; // If you're not using PDO and prepared statements you're doing it wrong, so i absolutely recommend you learning that if you haven't already.
$stmt->execute($values);
That should do the trick.
Notice, using prepared statements frees you from manually escaping your data. However, if you're concerned about XSS attacks, you still should use strip_tags of a filter extension.