A transaction is a unit of program execution that accesses and possibly updates
various data items. Usually, a transaction is initiated by a user program written
in a high-level data-manipulation language (typically SQL), or programming language
(for example, C++, or Java), with embedded database accesses in JDBC or
ODBC. A transaction is delimited by statements (or function calls) of the form
begin transaction and end transaction. The transaction consists of all operations
executed between the begin transaction and end transaction.