Question

I’m trying to write small program that will generate my DB tables, sequences and trigger from code, using NHibernate.

With SchemaExport.Create() method I was able to create all the table and relevant sequences, but I was not able to create triggers. Therefore I tried to use session.CreateSQLQuery() to run command that adds the trigger to the DB.

My code looks like this:

string createTriggerQuery= @"create or replace trigger table_insert_trigger before insert on Table for each row begin select TableSequence.nextval into :new.ID from dual; end;";
var query = session.CreateSQLQuery(createTriggerQuery);
query.ExecuteUpdate();

The query works as I run it on the Oracle SQL Developer, but as I execute my code I’m getting this exception:

Could not execute native bulk manipulation query:create or replace trigger... [SQL: SQL not available]

I also tried to use HBM queries to create the query. I add XML file to the project as embedded resource and on it I add the following code:

<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
<database-object>
    <create>
        create or replace
        trigger table_insert_trigger before insert on table
        for each row
        when (new.ID is NULL)
        begin
        select tableSequence.nextval into :new.ID from dual;
        end;
    </create>

and in my FluentConfiguration member I configured it to add hbm mapping:

_fluentConfiguration.Mappings(m => m.HbmMappings.AddFromAssemblyOf<DbContextFactory>());

but that was not working either.

Does anyone know how can I add the trigger to my DB from code?

Answer 1

The problem in this particular instance is the query you are trying to execute against the database, specifically this part:

... into :new.ID from dual;

The colon (:) is being interpreted by NHibernate as an indicator of a parameter, and substituting it with ? (since you aren’t actually passing a parameter). So it is actually passing an SQL that looks like this,

into ? from dual

At which point Oracle complains.

Currently, there is no way for NHibernate to escape the : and pass it literally to the database, as noted here.

Under a similar constraint, the solution was to use an ORM other than NHibernate. If this is the required purpose, maybe NHibernate is not the best option.