Socket IO how to implement connection to Mysql?

Question

Node.js

Friends, hello.
I'm learning websocket, so far I just started, so all the skills that I have add up to a simple chat. I analyzed various projects that work with real time mode and found that they use a database connection and send this data to the client.
For example:
upx . cash ( lottery site )
nvuti . live (table with games)
Question:
How can I implement getting data from the database in Socket IO and updating the table? (On the sites that are above, femmes fly every second, and they come from the database)
As I think:
1) Connect to the database in the node
2) send this data to the socket
But how to send it constantly so that performance does not suffer

Answer 1

But how to send them constantly so that performance does not suffer

learn to store data correctly in the database and use indexes, partitions, etc.
https://ru.wikipedia.org/wiki/%D0%9D%D0%BE%D1%80%D...
https://ru.wikipedia.org/wiki/%D0%98%D0%BD% D0%B4%D...