ADO.NET data provider for Oracle is dying. ADO.NET team has decided to kill(deprecate) it in .NET 4.0. How sad isn’t it? Read more about the story on ADO.NET team blog

Though sometimes I feel its unnecessary to have a duplicate copy of Oracle data provider. Most of the people use ODP.NET or some other third party client. Nice comparison here (and that is why people don’t use .NET Oracle client :))

One very bad thing I noticed about these providers is both of them need Oracle client installed. For the MS provider(System.Data.OracleClient) the minimum requirement is Oracle 8i Release 3 (8.1.7) Client or later. Check the requirement in detail here System Requirements (Oracle).
For the ODP.NET Oracle client version 9.2 or later.

Its not always possible to install a large application like Oracle client in some scenario, so there is an alternative without installing the Oracle client, use Oracle Database Instant Client. Just put Oracle Instant Client in the same folder as your executable file.

-Rujith