Question

I need to run a SQL Query in vb.net to find the average rating for my application. I think this is the correct SQL for doing this:

SELECT AVG(Rating) FROM Feedback;

The only problem is im not sure how to run this query correctly. I had a similar query which I have changed to the following(It doesnt work) and I just wondered if you could help adapt this so it actually works?

    Dim conn As New MySqlConnection(DBCred)
    Dim sqlquery As String = "SELECT AVG(Rating) FROM Feedback;"
    Dim cmd As MySqlCommand
    Dim AVGRating As String
    conn.Close()
    cmd = New MySqlCommand(sqlquery, conn)
    conn.Open()
    Try
        AVGRating = cmd.r
    Finally
        cmd.Connection.Close()

    End Try
    conn.Close()

thanks
Chris

Answer 1

try this one.

    Dim AVGRating As String = String.Empty
    Using xConn As New MySqlConnection(DBCred)
        Using xComm As New MySqlCommand()
            With xComm
                .Connection = xConn
                .CommandType = CommandType.Text
                .CommandText = "SELECT AVG(Rating) FROM Feedback WHERE Feedback.Rating > 0"
            End With
            Try
                xConn.Open()
                AVGRating = CStr(xComm.ExecuteScalar)
            Catch ex As Exception
                MsgBox(ex.Message.ToString)
            Finally
                xConn.Close()
            End Try
        End Using
    End Using

Link: ADO.NET ExecuteScalar in SqlCommand Object