Using first and last - collection method, PL-SQL Programming

Using FIRST and LAST

FIRST and LAST return the first and last (minimum and maximum) index numbers in a collection. When the collection is empty, the FIRST and LAST return NULL. If the collections contains only one element, the FIRST and LAST return the same index number, as the example below shows:

IF courses.FIRST = courses.LAST THEN ... -- only one element

The later example shows that you can use FIRST and LAST to specify the lower and upper bounds of a loop range provided each element in that range exists:

FOR i IN courses.FIRST..courses.LAST LOOP ...

However, you can use the FIRST or LAST where the integer expression is allowed. In the example below, you use FIRST to initialize the loop counter:

i := courses.FIRST;

WHILE i IS NOT NULL LOOP...

For varrays, the FIRST always returns 1 and LAST always equals to COUNT. For the nested tables, FIRST generally returns 1. But, if you delete elements from the beginning of the nested table, FIRST returns a number bigger than 1. Also for the nested tables, the LAST generally equals to COUNT. But, if you delete elements from the middle of a nested table, the LAST becomes larger than COUNT.

Posted Date: 10/4/2012 3:15:27 AM | Location : United States







Related Discussions:- Using first and last - collection method, Assignment Help, Ask Question on Using first and last - collection method, Get Answer, Expert's Help, Using first and last - collection method Discussions

Write discussion on Using first and last - collection method
Your posts are moderated
Related Questions
Identifiers You use identifiers to name the PL/SQL program items and units that include constants, variables, cursors, exceptions, cursor variables, subprograms, and packages.

Advantages of Exceptions Using the exceptions for the error handling has many benefits. Without an exception handling, every time you issue a command, you should ensure for th

Positional and Named Notation You can write the actual parameters when calling a subprogram, using either positional or named notation. That is, you can point to the relationsh

Use the NOCOPY Compiler Hint By default, the OUT and IN OUT parameters are passed by the value i.e. the value of an IN OUT actual parameter is copied into the corresponding fo

Parameter and Keyword Description: type_name: This identifies a user-defined type specifier that is used in the subsequent declarations of the objects. AUTHID Clause:

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

Joining in SQL Joining IS_CALLED and IS_ENROLLED_ON in SQL SELECT * FROM IS_CALLED NATURAL JOIN IS_ENROLLED_ON This is an example of an SQL table expression. I have been


Defining and Declaring Collections To create the collections, you must define a collection type, and then declare the collections of that type. You can define the VARRAY types a

This task involves developing some functions that extract data from an SQL database. The scenario is that a company which owns an online vehicle search website wants to generate so