Why data records in the database tables are erased?

When you run a web application created using php and MySQL.

From time to time the data records in database tables are erased. This happens randomly and often, until I placed the web application behind the firewall Sucuri. Recently had the same problem, and I was wondering what may be a malicious SQL injection which causes this problem.

We use Sucuri to monitor the implementation of the code but with the database I do not know if this is to prevent Sucuri.
April 3rd 20 at 17:24
2 answers
April 3rd 20 at 17:26
We do not use Sucuri and other third-party razgranicheniia accesses within the system.

We define the area of responsibility and correctly exposed right to access files inside the database (the rights of users of the database), and no problems with data loss in the database (and unauthorized modification of files) is not observed.
What You suggest!
April 3rd 20 at 17:28
You have logs?
Determine who, where, when and how you request cleans the database and close this hole

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