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

Question

I am 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 how much use the function mysqli_num_rows($link) of 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']}'");

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