Check if there is a deadlock in MySQL.

There are several methods to check if a deadlock has occurred in MySQL: 1. Use the SHOW ENGINE INNODB STATUS command: executing this command can provide information about the status of the InnoDB engine, including recent deadlock situations. Look for the “LATEST DETECTED DEADLOCK” section, where relevant information will be displayed if a deadlock has occurred. 2. Execute a SELECT statement: running a simple SELECT statement can help determine if a deadlock has occurred. If a deadlock has occurred, a “Deadlock found when trying to get lock” error will be thrown. 3. Query the information_schema.INNODB_LOCKS and information_schema.INNODB_LOCK_WAITS tables: using these tables can help identify transactions currently being locked and transactions waiting for locks. If there are transactions waiting for locks, and a situation of circular waiting arises, a deadlock may have occurred. 4. Monitoring tools: utilize MySQL monitoring tools such as Percona Toolkit or MySQL Enterprise Monitor to monitor and report deadlock situations. It is important to note that deadlocks are random events and may not occur frequently, therefore checking for deadlocks should be done over a suitable period of observation.