Message-Id: <10694.123123@fatcity.com>
From: Malik Michael <mmalyk@cryptologic.com>
Date: Tue, 28 Nov 2000 15:09:19 -0500
Subject: Re: Before insert trigger code

Hi Ranganath

For your case you can try to create trigger something like this (just
example):

create or replace trigger <trigger name> before insert on <table name>
for each row
DECLARE
row_count NUMBER;
BEGIN
SELECT count(*) INTO row_count from <table name> WHERE :new.start_dt BETWEEN
start_dt AND expiry_dt OR
:new.expiry_dt BETWEEN start_dt AND expiry_dt;
IF row_count>0 THEN
     dbms_output.put_line('Rejected by conditions ');
ELSE
    dbms_output.put_line('Approved by conditions ');
END IF;
END;
/

This trigger  returns resulting message (for example) and executing COMMIT or
ROLLBACK is up to you.

Regards

  Michael Malyk
  Oracle Programmer
  Toronto,Canada


RanganathK@lgcommerznow.com wrote:

> Dear all,
>
>      I have a table by name image_master  whose structure is as below:
>
>  IMAGE_NAME                                             NOT NULL
> VARCHAR2(60)
>  TYPE                                                              NOT NULL
> CHAR(1)
>  START_DT                                                  NOT NULL
> VARCHAR2(8)
>  EXPIRY_DT
> VARCHAR2(8)
>  IMAGE_DESC
> VARCHAR2(600)
>  CREATE_DT
> VARCHAR2(8)
>  MODIFY_DT
> VARCHAR2(8)
>
> The dates are entered in the form 'yyyymmdd'.  All the dates have been
> assigned the datatype as varchar2(8) instead of date for a specific reason.
> I would like to create a before insert trigger on the table so that the
> user cannot insert a record if the start_dt and expiry_dt overlap the
> existing start_dt and expiry_dt in the existing records.  For example,  if
> there is a record whose start_dt is 20001126 and end_dt is 20001128 then
> the user is not allowed to have start_dt and end_dt between 26th and 28th
> November, 2000 (both dates inclusive).  His start_dt and end_dt can be any
> dates apart from 26th, 27th and 28th November.   How do I implement this
> using SQL or PL/SQL?  Is there any other way out apart from creating a
> before insert trigger?   I hope I am clear.  Any help in this regard will
> be highly appreciated.
>
> TIA and regards,
>
> Ranganath
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author:
>   INET: RanganathK@lgcommerznow.com
>
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