VB.NET SQL Server Insert - ExecuteNonQuery: Connection property has not been initialized

Question

In the form load event, I connect to the SQL Server database:

Private Sub AddBook_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles My         


        

Answer 1

Pretty much what the error message implies - the Connection property of the SqlCommand object hasn't been assigned to the connection you opened (in this case you called it myConnection).

Also, a word of advice here. Do some reading on sql parameters - doing sql concatenation from user input without any sanity checks is the way SQL injection attacks happen.

This is one way to do it:

Private Sub cmdAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdAdd.Click
    Try
        myConnection.Open()
        myCommand = New SqlCommand( _
        "INSERT INTO tblBook(BookCode, BookTitle, Author, PublishingYear, Price, " & _
        "                    EnterDate, CatID, RackID, Amount) " & _
        "VALUES(@bookCode, @bookTitle, @author, @publishingYear, @price, @enterDate, " & _
        "       @catId, @rackId, @amount)")
        myCommand.Connection = myConnection
        with myCommand.Parameters
            .AddWithValue("bookCode", txtBookCode.Text)
            .AddWithValue("bookTitle", txtTitle.Text)
            .AddWithValue("author", txtAuthor.Text)
            .AddWithValue("publishingYear", txtPublishYear.Text)
            .AddWithValue("price", txtPrice.Text)
            .AddWithValue("enterDate", txtEnterDate.Text)
            .AddWithValue("catId", txtCategory.Text)
            .AddWithValue("rackId", txtRack.Text)
            .AddWithValue("amount", txtAmount.Text)
        end with
        myCommand.ExecuteNonQuery()
        MsgBox("The book named '" & txtTitle.Text & "' has been inseted successfully")
        ClearBox()
    Catch ex As Exception
        MsgBox(ex.Message())
    End Try
    myConnection.Close()
End Sub