April 2002
Intermediate to advanced
336 pages
9h 58m
English
Content preview from Mastering Oracle SQLBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Procedures, Functions, and Packages
Although PL/SQL can still be used to write scripts, also known as anonymous blocks , the focus of this chapter is PL/SQL routines stored in the Oracle server. PL/SQL routines stored in the database may be one of two types: stored procedures or stored functions. [24]
Stored functions and procedures are essentially identical except for the following:
Stored functions have a return type, whereas procedures do not.
Because stored functions return a value, they can be used in expressions, whereas procedures cannot.
Stored functions and procedures may be compiled individually, or they may be grouped together into packages. Along with being a convenient way to group related functionality together, packages are important for the following reasons:
Packages are loaded into memory as a whole, increasing the likelihood that a procedure or function will be resident in memory when called.
Packages can include private elements, allowing logic to be hidden from view.
Placing functions and procedures inside packages eliminates the need to recompile all functions and procedures that reference a newly-recompiled one.
Function and procedure names may be overloaded within packages, whereas standalone functions and procedures cannot be overloaded.
Functions and procedures inside packages can be checked for side effects at compile time rather than at execution time, which improves performance.
If these reasons haven’t convinced you to place your stored functions ...
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