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Trigger question
Posted by: personal private
Date: October 06, 2014 09:42AM

I know this question has been asked before, but my Google foo is failing me.

I want to make a trigger like the following:
Begin
if NEW.string_field LIKE "string litteral" THEN
***THis is my issue**
I need to reject the insert and respond with a message like
"string_field must not be the default value."
end if
end

(Obviously the semi colons are missing from the example)

Use case: In a data base we have a 'comment' column. This column stores information which is both a comment, and to help people using software which uses the database to understand what material they are selecting. The field has a default value of "Enter an end user useful comment here, to serve as a description". If a new record is added, and the field has not been changed, I need it to kick out a message that the person entering the data will see, and refuse to write the data.

So question 1:
Can this be done from a trigger?

Question 2:
(If Q1 is true) Can this be done without creating a custom exception? (please provide example as I am new to MySQL triggers/roputines/functions)

Question 3:
(If Q2 is false) How do create and use a custom exception for this (hopefully from the trigger) (If I have to go this route I have no idea how to, so please provide an example or a link to an example....)?

Any help would be appreciated.
C. Jason B.

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