Question

I am using this code to get data:

 Dim connetionString As String
    Dim connection As SqlConnection
    Dim sqlq As String

    sqlq = "select top 1 * from table1 where smth"

    Dim ds As New DataSet
    connetionString = "Data Source=db;Initial Catalog=ic;User ID=id;Password=pass"
    connection = New SqlConnection(connetionString)

    Try
        Using connection
            Dim command As SqlCommand = New SqlCommand(sqlq, connection)
            connection.Open()
            Dim reader As SqlDataReader = command.ExecuteReader()
            If reader.HasRows Then
                Do While reader.Read()
                    x = reader.GetString(5)
                Loop
            End If
            reader.Close()
        End Using
    Catch ex As Exception
    End Try

This type of connection (with different sqlq [query]) I use a lot in diffenrent functions and every time I close the connection. I want to optimize it so it would take less time to get data. How do I do that?

Answer 1

It is best practise to always dispose/close a connection as soon as you’re finished with it. Actually the connection-pool will not close the underlying physical connection but only flag this connection as reusable if it is closed. So if you don’t close a connection it cannot be reused, hence the pool needs to create a new physical connection which is very expensive.

So only some minor improvements:

Const sql = "select top 1 * from table1 where smth"
Dim table As New DataTable()

Using con = New SqlConnection("Data Source=db;Init ....")
    Using command = New SqlCommand(sql, con)
        Using da= New SqlDataAdapter(command)
            da.Fill(table)
        End Using
    End Using
End Using

You should use Using for any object implementing IDisposable. You should not use an empty Catch block.