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nhibernateopenedgedialect

Select top using NHibernate custom dialect to OpenEdge database does not work

I have made a custom dialect to be able to use NHibernate with a Progress/OpenEdge database over ODBC. In most cases the dialect works fine, but I have a problem with SELECT TOP statements. The problem is that the statements are generated as the following with the amount of columns to return as a parameter:

SELECT TOP ? SomeColumn
FROM SomeTable
where SomeColumn = ?; p0 = 100, p1 = 'test'

The Progress/Openedge database does not support this, so I would like to make some changes to the dialect, forcing the statement to not use parameters for the amount of columns in SELECT TOP - like this:

SELECT TOP 100 SomeColumn
FROM SomeTable
where SomeColumn = ?; p0 = 'test'

Is this possible?

By the way, im using NHibernate v. 3.3.1

Solution

  • By looking at NHibernate's source code, I would say that you need to override SupportsVariableLimit property to return false.

    /// <summary>
/// Can parameters be used for a statement containing a LIMIT?
/// </summary>
public override bool SupportsVariableLimit
{
    get { return false; }
}

    Edit

    Unfortunately, it seems that NHibernate Linq doesn't use SupportsVariableLimit property. It always tries to use parameters.

    Here's a discussion on that, with a source code fix.