Hi,

I am net to NHibernate, and I hava a read baisc/general question.

In my database (PostgreSQL), I have an unique index laying on the field transaktionsnummer which is located in the table payment.

I use the Find-Method of the Session class to query some objects:

ArrayList find = (ArrayList)Program.Session.Find("from payment where transaktionsnummer = ? ", transaktionsnummer, NHibernateUtil.Int32);

What now happens amazes me: I get an Db-Exception "duplicate key violates unique constraint uind_transaktionsnummer"

So my general question is: the Find-Method should be Read-Only, shouldn't it? How can a querying function trhow a uniqe constraint exception? It isn't supposed to write someting, or am I completely wrong?

thanks for any Hints,

Bernd

It would help to see the code for your Payment class and maybe the mapping file. I don't really know what PostgreSQL is trying to do here, but I will make some comments about the HQL that may or may not help.

When you write an HQL query, you are using classes and properties, and HQL is case sensitive. I am guessing that your payment class is actually Payment and possibly the transaktionsnummer(sic) property is cased more like TransaktionsNummer. I would start by changing your query to...


In the example I give, "Payment" is the class that I want to query from. "p" is an alias. "TransaktionsNummer" is a property in the Payment class. Both "Payment" and "TransaktionsNummer" should be cased the same as they are in your code files. The alias can be anything you want as long as it is consistent within the HQL query.

I don't know that this will solve your problem, but I hope it helps. If you still need help, try submitting your class and hbm.xml files. Also, enabling the NHibernate.SQL logger in the Log4Net logs will allow you to see the SQL that is being sent to the database so that you can get a better idea of what is happening.