Duplicated values

[David Villalobos Cambronero]

Hi, I have a problem, I´m triying to insert values into a table, but there is a restriction, if some values are iqual the trigger has to show me an error.

I,ve triying to do this, but I can´t. Can someone helpme.

PD, attached an example:

INSERT INTO Curses VALUES ('Name', 'Second Name', 1, 1);

In this case I need a error mesage, because there are tow numbers 1.

Thanks.

David