mysqli_query () always returns true even when it does not change registry update

I'm running the query in the database:

UPDATE store SET status = '0' WHERE id ='325'

And always returns true even if the value is not updated, and when I use the mysqli_num_rows($link) function of the parameter error mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given ,

The query is formed like this:

Update('store', array('status' => 0), "id ={$arr['store]['id']}'");

Parameters are: tabela , array campos=>valor and cláusula where