Recursion versus iteration, PL-SQL Programming

Assignment Help:

Recursion versus Iteration

Dissimilar the iteration, recursion is not crucial to PL/SQL programming. Any problem which can be solved using recursion can be solving using the iteration. Also, the iterative version of the subprogram is typically easier to design than the recursive version. Though, the recursive version is typically simpler, smaller, and hence easier to debug. Compare the functions below that calculate the nth Fibonacci number:

-- recursive version

FUNCTION fib (n POSITIVE) RETURN INTEGER IS

BEGIN

IF (n = 1) OR (n = 2) THEN

RETURN 1;

ELSE

RETURN fib(n - 1) + fib(n - 2);

END IF;

END fib;

-- iterative version

FUNCTION fib (n POSITIVE) RETURN INTEGER IS

pos1 INTEGER := 1;

pos2 INTEGER := 0;

cum INTEGER;

BEGIN

IF (n = 1) OR (n = 2) THEN

RETURN 1;

ELSE

cum := pos1 + pos2;

FOR i IN 3..n LOOP

pos2 := pos1;

pos1 := cum;

cum := pos1 + pos2;

END LOOP;

RETURN cum;

END IF;

END fib;

The recursive version of the Fibonacci is more graceful than the iterative version. Though, the iterative version is more accurate; it runs faster and uses less storage. That is as each recursive call needs an additional time and memory. As the number of recursive calls gets bigger, so does the difference in effectiveness. Still, if you expect the number of recursive calls to be little, you may choose the recursive version for its readability.


Related Discussions:- Recursion versus iteration

Deriving predicates from predicates in sql, Deriving Predicates from Predic...

Deriving Predicates from Predicates in SQL The corresponding section in the theory book describes how predicates can be derived from predicates using (a) the logical connectiv

Organic evolution, Organi c Evolution Evolution is a slow continuou...

Organi c Evolution Evolution is a slow continuous, irreversible and natural process of change to give rise to advance and diverse forms of life i.e. formation of new specie

%notfound - explicit cursor attributes, %NOTFOUND The %NOTFOUND is log...

%NOTFOUND The %NOTFOUND is logical, opposite of the %FOUND. The %NOTFOUND yields FALSE if the last fetch returned a row, or TRUE when the final fetch failed to return a row. I

Cursor for loops, Cursor FOR Loops In most cases that need an explicit ...

Cursor FOR Loops In most cases that need an explicit cursor, you can simplify the coding by using a cursor FOR loop rather of the OPEN, FETCH, and CLOSE statements. A cursor FO

Null statement-sequential control, NULL Statement The NULL statement c...

NULL Statement The NULL statement clearly specifies in action; it does nothing other than to pass control to the next statement. It can, though, improve the readability. In a

Predefined exceptions, Predefined Exceptions The internal exception is ...

Predefined Exceptions The internal exception is raised implicitly whenever your PL/SQL program exceeds a system-dependent limit or violates an Oracle rule. Each & every Oracle

Packages, Packages The package is a schema object which groups logicall...

Packages The package is a schema object which groups logically associated to the PL/SQL items, types, and subprograms. The Packages have 2 sections: the specification & the bod

How pl/sql resolves the calls? , How Calls Are Resolved? The figure sho...

How Calls Are Resolved? The figure shows that how the PL/SQL compiler resolves the subprogram calls. When the compiler encounters the procedure or function call, it tries to di

Keyword & parameter description - expressions, Keyword & Parameter Descript...

Keyword & Parameter Description: boolean_expression: This is an expression which yields the Boolean value that is TRUE, FALSE, & NULL. character_expression: This

Raise_application_error, Raise_application_error -  procedure of package D...

Raise_application_error -  procedure of package DBMS_STANDARD , allows to issue an user_defined error messages by stored sub-program or database trigger.

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd