Error: Fill: selectcommand.connection property has not been - sql-server

Question

I'm trying to retrieve binary data from a database.
I got this error: "Error: Fill: selectcommand.connection property has not been". I can't locate the error.
Public Shared Function BinaryData(ByVal sFileName As String) As Byte()
Dim strSql As String
Dim binaryFile As Byte() = Nothing
Dim dt As DataTable
Dim myCommand As New SqlCommand
Dim sqlConn As New SqlConnection
sqlConn = New SqlConnection("Data Source=xxx;Initial Catalog=xx;Persist Security Info=True;User ID=wxx;Password=xx;MultipleActiveResultSets=True;Application Name=EntityFramework")
sqlConn.Open()
myCommand.Connection = sqlConn
strSql = "SELECT Data FROM tbldrive WHERE Filename = '" + sFileName + "'"
Dim scmd As New SqlCommand(strSql, sqlConn)
dt = DataComponent.DataTableQuery(DataComponent.SqlConn, strSql)
If dt.Rows.Count > 0 Then
Try
binaryFile = DirectCast(dt.Rows(0).Item("Data"), Byte())
Catch ex As Exception
MsgBox(ex.Message)
End Try
End If
Return binaryFile
End Function

Answer 1

It looks like you've tried a few things in that code but accidentally left the remains of some attempts in there.
There are some things you could do a bit differently: as you're only after one item from the database, you can use ExecuteScalar; and when the code has finished with the SQL connection and command, they should have .Dispose() called on them - the Using statement will take care of that for you even if something goes wrong. Finally, you should always use SQL parameters to pass parameters to an SQL query - it makes it more secure and avoids having to worry about things like apostrophes in the value.
Public Shared Function BinaryData(ByVal sFileName As String) As Byte()
Dim sql As String = "SELECT Data FROM tbldrive WHERE Filename = #fname"
Dim connStr = "Data Source=xxx;Initial Catalog=xx;Persist Security Info=True;User ID=wxx;Password=xx;MultipleActiveResultSets=True;Application Name=EntityFramework"
Dim binaryFile As Byte() = Nothing
Using conn As New SqlConnection(connStr),
cmd As New SqlCommand(sql, conn)
cmd.Parameters.Add(New SqlParameter With {
.ParameterName = "#fname",
.SqlDbType = SqlDbType.NVarChar,
.Size = 255,
.Value = sFileName})
conn.Open()
Dim obj As Object = cmd.ExecuteScalar()
If obj IsNot Nothing Then
Try
binaryFile = DirectCast(obj, Byte())
Catch ex As Exception
MsgBox(ex.Message)
End Try
End If
End Using
Return binaryFile
End Function
(You may need to adjust the .SqlDbType and .Size parameters: they need to match the column type and size in the database. Also, you probably don't need MultipleActiveResultSets.)

Answer 2

The problem seems to be that you have two SqlCommand objects:
Dim myCommand As New SqlCommand
...
myCommand.Connection = sqlConn
It's assigned but not used.
Then you have defined another one:
Dim scmd As New SqlCommand(strSql, sqlConn)
that is not used either.
And I don't know why you have this:
dt = DataComponent.DataTableQuery(DataComponent.SqlConn, strSql)
Do you even need a SqlCommand if you are not using it ?
Clean up your code by removing unused variables.