SQL DB export using powershell - sql

Question

I am attempting to export BLOB data for images stored in a remote SQL server and save them to an export folder in .jpg on the local machine. Any assistance in troubleshooting the first error or helping me modify the working connection to pull the blob data and convert it to .jpgs on the local machine would be much appreciated.
I found the following code
$Server = "?????"
$Database = "??????"
$Dest = "c:\Export\"
$bufferSize = 8192
$sqlCommand = " SELECT ID?????1
FROM dbo.W?????e; "
$authentication = "Integrated Security=SSPI;"
$connectionString = "Provider=sqloledb; " +
"Data Source=$dataSource; " +
"Initial Catalog=$database; " +
"$authentication; "
$connection = New-Object System.Data.OleDb.OleDbConnection $connectionString
$command = New-Object System.Data.OleDb.OleDbCommand $sqlCommand,$connection
$connection.Open()
$reader = $command.ExecuteReader()
$out = [array]::CreateInstance('Byte', $bufferSize)
While ($reader.Read())
{
$fileStream = New-Object System.IO.FileStream ($Dest + $reader.GetString(0)), Create, Write
$binaryWriter = New-Object System.IO.BinaryWriter $fileStream
$start = 0
$received = $reader.GetBytes(1, $start, $out, 0, $bufferSize - 1)
While ($received -gt 0)
{
$binaryWriter.Write($out, 0, $received)
$binaryWriter.Flush()
$start += $received
$received = $reader.GetBytes(1, $start, $out, 0, $bufferSize - 1)
}
$binaryWriter.Close()
$fileStream.Close()
}
$fileStream.Dispose()
$reader.Close()
$command.Dispose()
$connection.Close()
I am getting errors when running the code.
I can connect to the database using this code, but I dont understand the streamprocess enough to mesh the code to do what I want
$Server = "?????"; # SQL Server Instance.
$Database = "?????";
$Dest = "c:\Export\"; # Path to export to.
$bufferSize = 8192; # Stream buffer size in bytes.
$connString = "data source=?????,1433;Initial catalog=?????;Integrated Security=TRUE;"
$QueryText = "SELECT ID?????1
FROM dbo.W??????e;"
$SqlConnection = new-object System.Data.SqlClient.SqlConnection
$SqlConnection.ConnectionString = $connString
$SqlCommand = $SqlConnection.CreateCommand()
$SqlCommand.CommandText = $QueryText
$DataAdapter = new-object System.Data.SqlClient.SqlDataAdapter $SqlCommand
$dataset = new-object System.Data.Dataset
$DataAdapter.Fill($dataset)
$dataset.Tables[0]
Write-Output ("Finished");
This is what I am trying to accomplish, but I am getting errors casting the bytes to string
HERE

Answer 1

I bet your command timeout is too short. By default, it is 30 seconds. Blobs are usually very large, and I wouldn't be surprised if it is taking longer than 30 seconds to read them all from the database. Try setting the timeout to something really, really large:
$command.CommandTimeout = [Int32]::MaxValue

Answer 2

I got the same error.
Reading the original code a little closer the SQL Server name is for an instance. If you are executing this on the local server you can use "." as the server name.
$Server = ".";