Free Trial

Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.

  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint
Share this Page URL
Help

6. Advanced DBI > Transactions, Locking, and Isolation

Transactions, Locking, and Isolation

The final topic in this chapter deals with the important (and hair-raising!) topic of transaction handling.

Transaction handling is a feature of the more powerful database systems in which SQL statements can be grouped into logical chunks. Each chunk is known as a transaction, and the operations it performs are guaranteed to be atomic for the purposes of recovery. According to the ANSI/ISO SQL standard, a transaction begins with the first executable SQL statement and ends when it is explicitly committed or rolled back.

The process of committing data writes it into the database tables and make it visible to other concurrent users. Rolling back discards any changes that have been made to any tables since the beginning of the current transaction.


  

You are currently reading a PREVIEW of this book.

                                                                                                                    

Get instant access to over $1 million worth of books and videos.

  

Start a Free 10-Day Trial


  
  • Safari Books Online
  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint