Regarding mysqli, does it need to be closed manually after execution?

Question

1.mysqli_connect After the connection is completed, the sql operation is completed. Do I need to do manual operation?

2.mysqli_connect When querying and modifying are executed successively, is the link character reused, or is it reconnected every time it is executed?

These two problems have been bothering me for a long time. In my project, reconnection and manual shutdown are required, but some mysql classes do not have these. If not, then yes There can be very little and a lot of code