PDO UPDATE不更新数据库

My update statement dosn't seem to be updating my database but I'm unsure why, I've used the same code elsewhere in my script and it works fine.

try
{
    // update the live documents details
    $sth = $conn->prepare("UPDATE docs SET ref = :ref, rev = :rev, updated = :updated WHERE id = :id");
    $sth->bindParam(':ref', $ref);
    $sth->bindParam(':rev', $rev);
    $sth->bindParam(':updated', $date);
    $sth->bindParam(':id', $currentid);
    $sth->execute();
}
catch(Exception $e)
{
    throw new Your_Exception($e->getMessage());
    // or
    throw $e;
}

I've tried manually inputting a query into the database using PHPMyAdmin just to test I have my table names correct and the query does work as expected.

UPDATE docs SET ref =  'FMS',
rev =  'D',
updated = NOW( ) WHERE id =73

So this leaves me thinking I have an error in my PDO statement. Although the try catch block isn't giving any errors.

There are all possible reasons

• there is an error in the query (which have to be thrown)
• there is no data to match the criteria.
• the data is already updated - nothing to change.
• you are checking not the table/database which you were updating.

Please verify all the issues listed.

By the way, to be able to see thrown errors you have to configure PHP properly