Transaction isolation level and transaction processing of InnoDB Storage engine in MySQL

The transaction isolation level of the InnoDB Storage engine in MySQL is different from that in transaction processing. 1. The set transaction command cannot be used to change the isolation level. However, you can use set {global | session} transaction to change the isolation level. In this document, set transaction can change the isolation level of the next transaction in the current session. It cannot be used in actual tests. 2. Use set [{global | session}] tx_isolation = {READ-COMMITTED | REPEATABLE-READ} to change the transaction isolation level. 3. read committed isolation level. Binary logs must be in row format, or binary logs are not enabled. 4. When autocommit is OFF, a new transaction is started immediately after the previous transaction ends (rollback or commit. Snapshot point of the transaction, which is the time point at which the first SQL statement (SELECT, DML) in the transaction is executed. 5. When autocommit is ON, a new transaction is started immediately after each SQL statement (SELECT, DML) ends. Snapshot point of the transaction, which is the time point at which the (unique) SQL statement (SELECT, DML) in the transaction is executed. 6. start the transaction statement to start a new transaction immediately. Snapshot point of the transaction, which is the time point at which the first SQL statement (SELECT, DML) in the transaction is executed. 7. After the start transaction statement, a transaction is terminated without executing commit or rollback. If you execute the start transaction statement again, the transaction before the start transaction is implicitly committed, and then a new transaction is started.