July 2011
Intermediate to advanced
516 pages
14h 50m
English
book
Expert PL/SQL Practices for Oracle Developers and DBAs
by John Beresniewicz, Adrian Billington, Martin Büchi, Melanie Caffrey, Ron Crisco, Lewis Cunningham, Dominic Delmolino, Sue Harper, Torben Holm, Connor McDonald, Arup Nanda, Stephan Petit, Michael Rosenblum, Robyn Sands, Riyaj Shamsudeen
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C H A P T E R 9
PL/SQL from SQL
Functions are an integral part of any well-designed PL/SQL application. They are an embodiment of programming best practices, such as code modularization, reuse, and the encapsulation of business or application logic. When used as simple building-blocks for larger programs, they can be an elegant and simple way to extend functionality while reducing code-complexity at minimal cost.
Conversely, when PL/SQL functions are heavily used, particularly in SQL statements, there can be a range of associated costs, most notably for performance. Depending on the nature of the function, simply calling PL/SQL from SQL and/or excessive I/O can degrade performance of even the most trivial of queries. ...