How to close a mysql connection with php?

The information in the PHP Manual is very poor about closing mysqli connections. It doesn't even indicate how to do it using the object-oriented style. In fact, the connection can be closed in two ways.

A. Object Oriented Style

$conn->close();

B. Procedural Style

mysqli_close($conn);

If you want to have consistent code, without mixing styles, I would recommend using option A. , since when creating the connection you used the object-oriented style:

$conn = new mysqli($HOST, $USUARIO, $PASSWORD, $DB);

Mixing styles is considered a bad practice.

It is also important to note that the Manual indicates this in a note:

mysqli_close()it will not close persistent connections. For more details, see the man page on persistent connections .

_{Closing mysqli connections in the PHP Manual}

Use the built-in function

mysqli_close($conn);