What are the different locking strategies in SQL?

What are the different locking strategies in SQL?

In SQL, there are several locking strategies, including optimistic locking, pessimistic locking, and row-level locking. Would you like to know more about each?

Yes, please explain optimistic and pessimistic locking.

Optimistic locking assumes that multiple transactions can complete without affecting each other. It checks for conflicts before committing. Pessimistic locking, on the other hand, locks resources as soon as they are accessed, preventing other transactions from modifying them until the lock is released.

When should I use each strategy?

Use optimistic locking when conflicts are rare and performance is a priority. Pessimistic locking is better when conflicts are frequent or when data integrity is critical.

Can you give an example of how to implement these in SQL?

Sure! For optimistic locking, you can use a version number in your table. For pessimistic locking, you can use the SELECT ... FOR UPDATE statement to lock rows.