ArcObjects – How do I Remove a Join Between a Standalone Table and Feature Layer?

arcobjectsattribute-joins

I already know how to do a table join with ArcObjects, via the IDisplayTable, IMemoryRelationshipClassFactory etc. interfaces. Here are some links to resources that have example code for this:

What I need to know is, how do I undo, i.e. remove such a join?

Once I've joined a standalone table to a feature layer, I end up with references to:

  • an IRelationshipClass (resulting from the join operation);

  • an ITable/IStandaloneTable/IDisplayTable (the table that was joined to the feature layer); and

  • an IFeatureLayer (the feature layer to which the table was joined).

Do these interfaces, or rather the objects behind them, allow unjoining at all? I've seen that IRelationshipClass has various DeleteRelationship… methods, but I can't see how they could work towards that end.

Best Answer

Code below works for me for a featurelayer. Similar logic could be used for a standalone table.

private void RemoveAllJoins(IFeatureLayer fLayer)
{
    var dispTable = fLayer as IDisplayTable;
    var rqt = dispTable.DisplayTable as IRelQueryTable;
    if (rqt != null)
    {
        Debug.Print("source: {0}", ((IDataset)rqt.DestinationTable).Name);
        Debug.Print("dest: {0}", ((IDataset)rqt.SourceTable).Name);
        fLayer.FeatureClass = (IFeatureClass)rqt.DestinationTable;
    }
    else
        Debug.Print("there are no joins");
}

The documentation for IRelQueryTable at 10 seems to be missing this important graphic, that appears in 8.3 help doc:

enter image description here

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