Why can't I suddenly retrieve data from the database (mysql? Solution

Why can't I suddenly retrieve data from the database (mysql? The host of the website's Western Digital used to run well. the customer's data retrieval and my background management data were okay. as a result, when I looked at background management today, all the data was 0, if no data is obtained, 0 is displayed .. Then I went to the management page of Western Digital to see if there was a problem with the database data. Why didn't I suddenly get the data in the database (mysql?
Hosts of the website's Western Digital
It has been running well in the past, and it is okay for customers to retrieve data from our backend management.
As a result, when I looked at the background management today, all the data was 0. when I defined that no data was obtained, it would show 0 ..
Then I went to the management page of Western Digital to see if there was a problem with the database data and found that the data was still there.

Then I tried to get the data from the front-end and the result was obtained.
Go to the background management page to refresh the data, and the data is displayed again ..
What is the problem.
The background shows that no customer has obtained data since today.
If this happens again in the future, it is true.
The cause is not found.

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Query mysql logs