More on Isolation - read phenomena

The ANSI/ISO standard SQL 92 refers to three different read phenomena when a transaction reads data that another transaction might have changed. These are dirty reads (when a transaction is allowed to read data from a row that has been modified by another running transaction and not yet committed), non-repeatable reads (during the course of a transaction, a row is retrieved twice and the values within the row differ between reads) and phantom reads (when, in the course of a transaction, new rows are added or removed by another transaction to the records being read).