add-type -path "C:oracleproduct12.1.0client_1ODP.NETmanagedcommonOracle.ManagedDataAccess.dll"
$username = "XXXX"
$password = "XXXX"
$data_source = "(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=XXXX)(PORT=XXXX))(CONNECT_DATA = (SERVER=dedicated)(SERVICE_NAME=XXXX)))"
$connection_string = "User Id=$username;Password=$password;Data Source=$data_source"

try{
    $con = New-Object Oracle.ManagedDataAccess.Client.OracleConnection($connection_string)

    $con.Open()
} catch {
    Write-Error (“Can’t open connection: {0}`n{1}” -f `
        $con.ConnectionString, $_.Exception.ToString())
} finally{
    if ($con.State -eq ‘Open’) { $con.close() }
}

C:UsersXXXXDesktoporacle_test.ps1 : Can’t open connection: User Id=XXXX;Password=XXXX;Data Source=(DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=XXXX)(PORT=XXXX))(CONNECT_DATA =
(SERVER=dedicated)(SERVICE_NAME=XXXX)))
System.Management.Automation.MethodInvocationException: Exception calling "Open" with "0" argument(s): "The type initializer for 'Oracle.ManagedDataAccess.Types.TimeStamp' threw an exception." --->
System.TypeInitializationException: The type initializer for 'Oracle.ManagedDataAccess.Types.TimeStamp' threw an exception. ---> System.Runtime.Serialization.SerializationException: Unable to find assembly
'Oracle.ManagedDataAccess, Version=4.121.2.0, Culture=neutral, PublicKeyToken=XXXX'.
   at OracleInternal.Common.OracleTimeZone.GetInstance()
   at Oracle.ManagedDataAccess.Types.TimeStamp..cctor()
   --- End of inner exception stack trace ---
   at OracleInternal.ConnectionPool.PoolManager`3.CreateNewPR(Int32 reqCount, Boolean bForPoolPopulation, ConnectionString csWithDiffOrNewPwd, String instanceName)
   at OracleInternal.ConnectionPool.PoolManager`3.Get(ConnectionString csWithDiffOrNewPwd, Boolean bGetForApp, String affinityInstanceName, Boolean bForceMatch)
   at OracleInternal.ConnectionPool.OraclePoolManager.Get(ConnectionString csWithNewPassword, Boolean bGetForApp, String affinityInstanceName, Boolean bForceMatch)
   at OracleInternal.ConnectionPool.OracleConnectionDispenser`3.Get(ConnectionString cs, PM conPM, ConnectionString pmCS, SecureString securedPassword, SecureString securedProxyPassword)
   at Oracle.ManagedDataAccess.Client.OracleConnection.Open()
   at CallSite.Target(Closure , CallSite , Object )
   --- End of inner exception stack trace ---
   at System.Management.Automation.ExceptionHandlingOps.CheckActionPreference(FunctionContext funcContext, Exception exception)
   at System.Management.Automation.Interpreter.ActionCallInstruction`2.Run(InterpretedFrame frame)
   at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame frame)
   at System.Management.Automation.Interpreter.EnterTryCatchFinallyInstruction.Run(InterpretedFrame frame)
    + CategoryInfo          : NotSpecified: (:) [Write-Error], WriteErrorException
    + FullyQualifiedErrorId : Microsoft.PowerShell.Commands.WriteErrorException,oracle_test.ps1

add-type -AssemblyName System.Data.OracleClient

$username = "XXXX"
$password = "XXXX"
$data_source = "XXXX"
$connection_string = "User Id=$username;Password=$password;Data Source=$data_source"

$statement = "select level, level + 1 as Test from dual CONNECT BY LEVEL <= 10"

try{
    $con = New-Object System.Data.OracleClient.OracleConnection($connection_string)

    $con.Open()

    $cmd = $con.CreateCommand()
    $cmd.CommandText = $statement

    $result = $cmd.ExecuteReader()
    # Do something with the results...

} catch {
    Write-Error (“Database Exception: {0}`n{1}” -f `
        $con.ConnectionString, $_.Exception.ToString())
} finally{
    if ($con.State -eq ‘Open’) { $con.close() }
}