Using lightweight transactions

INSERT and UPDATE statements that use the IF clause support lightweight transactions, also known as Compare and Set (CAS).

1. Register a new user.

   INSERT INTO users (login, email, name, login_count)
     VALUES ('jdoe', 'jdoe@abc.com', 'Jane Doe', 1)
     IF NOT EXISTS;

2. Perform a CAS operation against a row that does exist by adding the predicate for the operation at the end of the query. For example, reset Jane Doe's password.

   UPDATE users
     SET email = ‘janedoe@abc.com’
     WHERE login = 'jdoe'
     IF email = ‘jdoe@abc.com’;