How does MySQL handle optimistic locking and pessimistic locking?

There are two ways in MySQL to handle optimistic locking and pessimistic locking.

1. Optimistic Locking: In MySQL, optimistic locking can be achieved by using a version number or timestamp. A version number or timestamp field is added to the database table, and each time data is modified, the value of that field is queried first. When updating the data, the value of that field is incremented by 1 or updated to the current timestamp. Before committing the update operation, the version number or timestamp of the data is checked to see if it matches the value obtained during the previous query. If they match, the update is successful; if not, the update fails.
2. Pessimistic Lock: In MySQL, pessimistic locking can be achieved by using the SELECT … FOR UPDATE statement. When this statement is executed, MySQL will lock the selected data, preventing other transactions from modifying it until the current transaction is either committed or rolled back.

It is important to note that both optimistic locking and pessimistic locking have their own advantages and disadvantages, and the choice of which method to use should be based on specific business scenarios and needs.