Basic HTML version of Foils prepared 7 October 97

Foil 40 Data Concurrency and Consistency in Oracle -II

From Untitled presentation ARL Database Tutorial -- February 98. by Gang Cheng, C.W. Ou, Geoffrey C. Fox


Transaction - a logical unit of work that comprises one or more SQL statements executed by a single user
A transaction begins with the user's first executable SQL statement
A transaction ends when it is explicitly committed or rolled back
Transactions provide the database user or application developer with the capability of guaranteeing consistent changes to data, as long as the SQL statements within a transaction are grouped logically
A transaction should consist of all of the necessary parts for one logical unit of work - no more and no less
Data in all referenced tables are in a consistent state before the transaction begins and after it ends.
Transactions should consist of only the SQL statements that comprise one consistent change to the data



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