It seems the usage of System.Data.OracleClient is deprecated from .Net 4.0
http://blogs.msdn.com/adonet/archive/2009/06/15/system-data-oracleclient-update.aspx
Applications targeted at 4.0 will experience warnings/errors when System.Data.OracleClient is used. We may have to use ODP’s OracleClient.DataAccess instead.
However applications targeted at 2.0, 3.5 will continue to support System.Data.OracleClient.
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