Weird, Rick. I'm curious as to why we see different behavior even though we're both using "default behavior". There's obviously *something* that we've done differently, but at this point I don't have a clue. Oh well ...

~~Bonnie

>>Nope, the default for MissingSchemaAction is Add. It's the AddWithKey option that sets PK's and all that ... so, I don't think that's it. I bet you use DataRelations in your DataSets, which according to the docs (I'm looking at "Adding Constraints to a Table"), automatically adds ForeignKeyConstraints and UniqueConstraints to your DataTables. I'm not using DataSet DataRelations, so I'm guessing that that's why my default behavior is slightly different than your default behavior.
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>No, I don't use relations because all my relationships are set via object containership.
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>I can reliably dupe this by adding a couple of rows and trying to set the PK field to the same value when they are inside of a DataTable and I will get an exception.
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>There's lots of power there, but it's so woefully underdocumented it really bites...
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>+++ RIck ---