Database error for help

[kasynhk]

The error content displayed on the page is as follows:
There has been a critical error processing your request
Error: Table'./H100 /abc_online_customers' is marked as crashed and should be repaired
Error No: 145
DELETE FROM `abc_online_customers` WHERE `date_added`< (NOW()-INTERVAL 1 HOUR) in

In the same problem last week, I found the abc_online_customers form in Navicat and repaired it. At that time, the website was back to normal.

But the same error was reported today. What's more troublesome is that abc_online_customers is no longer found in Navicat. Where did it go? How to deal with it? Please help me, thanks!