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Non-Predefined Exception Example February 5, 2009

Filed under: PL/SQL — Akdora @ 11:47 am
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One of my friend asked me following question.

“I want to drop two columns of a table. So I wrote a basic drop command.

alter table t_test drop (col_name1, col_name2)

However, If this command is called more than once. I do not want an error message. What can I do for this?”

It’s a strange request, but this will learn us how to write a non-predefined  exception to solve this kind of requests. We can handle ORA-XXXXX exception as we want. We name them this numbered exceptions and handle them.  I will write a post about exception types as soon as possible. 

 When we try to drop a column that does not exists on the table. We get following error: ORA00904: invalid column name. It’s error number “-904”. We will use this number to define the exception.