Powershell - SQL Server - connectionstring in loop for multiple Instances - sql

Question

Thisis part of a bigger script which finds DatabaseFiles on a SQL Server machine (multiple instances).
Following should just return all files for 3 instances.
The server is called V3000801 and there is one default instance + 2 named instances on there. It's ok with me if either default or named doesn't work I'll work around this alone (most likely create a flag and do default with another connection string).
$SqlCmd.ExecuteNonQuery() just returns -1 which does not make any sense for me.
Thanks for the help
for($i=0;$i -lt $instances.Length;$i++){
$SqlConnection = New-Object System.Data.SqlClient.SqlConnection;
$Server= "V3000801\"+$instances[$i];
$SqlConnection.ConnectionString = "Server = $server ; Database = master; Integrated Security = sspi;trusted_connection=true";
$sqlQuery="SELECT physical_name FROM sys.master_files;";
Write-Host $SqlConnection.ConnectionString;
$SqlConnection.Open();
$SqlCmd = New-Object System.Data.SqlClient.SqlCommand;
$SqlCmd.CommandText = $sqlQuery;
$SqlCmd.Connection = $SqlConnection;
$SqlCmd.ExecuteNonQuery();
$SqlConnection.Close();
}

Answer 1

the link posted by #jody contains some good information
try:
$dr= $SqlCmd.ExecuteReader()
while ($dr.Read())
{
$dr.GetValue(0)
}
$sqlconnection.Close()

Answer 2

Use the ExecuteReader function for selects. ExecuteNonQuery is used for operations that do not return any results such as inserts, updates and deletes.
Here is an example in .NET but it should be similar in PowerShell.
EDIT:
This code should work. I tried it out on my own environment (with a different server name).
for($i=0;$i -lt $instances.Length;$i++){
$SqlConnection = New-Object System.Data.SqlClient.SqlConnection;
$Server= "V3000801\"+$instances[$i];
$SqlConnection.ConnectionString = "Server = $server ; Database = master; Integrated Security = sspi;trusted_connection=true";
$sqlQuery="SELECT physical_name FROM sys.master_files;";
Write-Host $SqlConnection.ConnectionString;
$SqlConnection.Open();
$SqlCmd = New-Object System.Data.SqlClient.SqlCommand;
$SqlCmd.CommandText = $sqlQuery;
$SqlCmd.Connection = $SqlConnection;
$reader = $SqlCmd.ExecuteReader();
while ($reader.Read())
{
"pfad=" $reader["physical_name"];
};
$SqlConnection.Close();
}