Problem with deleting data from contrlol block

Problem with deleting group data.
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I have a table called "student" which has information about all students. I want to create a form in which I will accept the following information:

        start year, start season, end year, end season.

Now I want to delete all the students who lie between those two dates.   eg. spring 91 to fall 93.

I am trying to write a ON-DELETE trigger to delete all the students but it is not working.

Please reply directly to my address.

PS: MY form does have only one control block that does not correspond to any base table.

		Thanks in Advance,
		Madhu.