Java Programming Language

Possible interaction between concurrent transactions is categorized as
follows:
n dirty reads occur when transactions are allowed to see uncommitted changes
to
the data. In other words, changes made inside a transaction are visible
outside the
transaction before they are commited. If the changes are rolled back instead
of
being committed, it is possible for other transactions to have done work
based on
incorrect, transient data.
n nonrepeatable reads occur when:
a. Transaction A reads a row
b. Transaction B changes the row
c. Transaction A reads the same row a second time and gets different results
n phantom reads occur when:
a. Transaction A reads all rows that satisfy a WHERE condition
b. Transaction B inserts an additional row that satisfies the same condition
c. Transaction A reevaluates the WHERE condition and picks up the additional
"phantom" row