to ADO or to ODP ?

I just read on System.Data.OracleClient Namespace that System.Data.OracleClient are deprecated.
The types in System.Data.OracleClient are deprecated. The types are supported in version 4 of the .NET Framework but will be removed in a future release. Microsoft recommends that you use a third-party Oracle provider.

The alternative is to use ODP (from Oracle) instead of ADO (from Microsoft). More powerful of course.

ADO (within powershell):

PS C:\> [Reflection.Assembly]::LoadWithPartialName("System.Data.OracleClient")

GAC Version Location
--- ------- --------
True v2.0.50727 C:\WINDOWS\assembly\GAC_32\\\

PS C:\> $connection=New-Object DATA.OracleClient.OracleConnection("Data Source=DB01;User Id=scott;Password=tiger")
PS C:\> $connection.Open()
PS C:\> (new-Object DATA.OracleClient.OracleCommand("select 'Hello World' from dual",$connection)).ExecuteScalar()
Hello World
PS C:\> $connection.Close()

PS C:\> [Reflection.Assembly]::LoadFile("C:\oracle\product\11.1.0\client_1\ODP.NET\bin\2.x\Oracle.DataAccess.dll")

GAC Version Location
--- ------- --------
True v2.0.50727 C:\WINDOWS\assembly\GAC_32\Oracle.DataAccess\\Oracle.DataAccess.dll

PS C:\> $connection=New-Object Oracle.DataAccess.Client.OracleConnection("Data Source=DB01; User Id=scott; password=tiger")
PS C:\> (new-object Oracle.DataAccess.Client.OracleCommand("select 'helloworld' from dual",$connection)).executescalar()
PS C:\> $connection.close()
PS C:\> $connection.dispose()

Read more : Oracle Data Provider for .NET Developer’s Guide

PS: also possible

PS> $dataset = New-Object Data.dataset
PS> (New-Object Oracle.DataAccess.Client.OracleDataAdapter("select * from emp",$connection)).fill($dataset)
PS> ($dataset.tables[0]|where{ $_.empno -eq 7902 }).ename