Question

I have mapped a class hierarchy using a table per subclass and it
works with Sql Server 2005.

However, when I try to use this same mapping against a Sql Compact 4.0
db, the generated insert statement is not working because it does not
include any column or value.

I’m using NH3.1.0-GA and MsSqlCe40Dialect.

The insert statement generated is:

INSERT INTO Element values ( )

And the mapping:

<class name="IElement" table ="Element">
    <id name="Id">
        <generator class="identity"/>
    </id>

    <joined-subclass name="TextElement" table ="TextElement">
        <key column="Id"/>
        <property name="Text" length="200"/>
    </joined-subclass>

    <joined-subclass name="NumberElement" table="NumberElement">
        <key column="Id"/>
        <property name="Value"/>
    </joined-subclass>

</class>

Thanks.

Answer 1

That’s definitely a bug (more precisely, a yet-unsupported scenario). I suggest you create an issue with a full repro test at http://jira.nhforge.org (you can link to this question)

The MSSQL syntax for a value-less insert is INSERT INTO <table> DEFAULT VALUES. This is defined in MsSql2000Dialect.NoColumnsInsertString.

The same code should probably be applied to MsSqlCe40Dialect (or MsSqlCeDialect if this syntax was available in previous versions, which I don’t know).

As a workaround, just inherit from MsSqlCe40Dialect and add the following:

public override string NoColumnsInsertString
{
    get { return "DEFAULT VALUES"; }
}

Of course, I’m assuming that is the correct syntax for SQL CE 4.