Results:

Check if the request is not blocked by other requests.

Use SHOW PROCESSLIST

Use SHOW ENGINE INNODB STATUS to view information about transactions in which InnoDB tables were involved.

Analyze the wrong result and correct the problem according to the result of the analysis.

Below is a list of techniques that we covered in the second part.

Reception # 11: use SHOW PROCESSLIST to view a list of simultaneous requests.

Reception number 12: use the INFORMATION_SCHEMA.PROCESSLIST table if you need a list of simultaneous queries sorted by any parameter.

Reception number 13: use SHOW ENGINE INNODB STATUS to get information about transactions.

Reception number 14: use the general query log if the output of SHOW ENGINE INNODB STATUS is only part of the information about the problem transaction.