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
Adding Table Constraints ALTER TABLE ENROLMENT ADD CONSTRAINT NameNotNull CHECK (Name IS NOT NULL) ; ALTER TABLE ENROLMENT ADD CONSTRAINT PK_StudentId_CourseId PRIM

set serveroutput on declare a number(5); b number(5); c number(5); begin a:=&a; b:=&b; c:=a/b; dbms_output.put_line(c); exception when zero_divide then d

Package Body: The package specification is implemented by the package body. That is, the package body has the definition of every cursor and the subprogram declared in the pac

UTL_FILE: The Package UTL_FILE permits your PL/SQL programs to read & write operating system (OS) text files. It gives a restricted version of the standard OS stream file I/O,

Updating Objects: To change the attributes of objects in an object table, you can use the UPDATE statement, as the illustration below shows: BEGIN UPDATE persons p SET p

I need SQL , WP SQL Expert Project Description: Expert required to modify WP SQL query. Skills required are MySQL, SQL, PHP, Wordpress

Question: (a) The objective of query optimization is to choose the most efficient strategy for implementing a given relational query, thereby improving the system performance. On

How Bulk Binds Improve Performance The assigning of values to the PL/SQL variables in SQL statements is known as binding. The binding of the whole collection at once is know

Overriding Default Locking By default, the Oracle locks the data structures for you automatically. Though, you can request exact data locks on rows or tables when it is to you

Use the PLS_INTEGER Datatype When you require to declare an integer variable, use the datatype PLS_INTEGER that is the most efficient numeric type. That is as the PLS_INTEGER