是否需要在单独的模块中分离连接代码 [英] Is it necessary to separate the connection code in a separate module

问题描述

嗨.在我的vb.net学习新旅程中，我朝着真正的编程实践迈进了一步.我在SQL Server 2008中有几种形式和2个表.数据发送和接收一切正常.

Hi. In my new journey of vb.net learning, I am stepping ahead in real programming practices. I have a couple of forms and 2 tables in SQL Server 2008. Data Sending and receiving is going all fine.

这是我在form1和Business_Info表单上的代码.

Here is my code on form1 and Business_Info Form.

Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click

        Dim con As New SqlConnection(cnStr) ' cnStr is declare as public in module
        Dim insQue As String = "Insert into Contact (Contact_ID, Name, Address, Cont_No) values (@Contact_ID, @Name, @Address, @Cont_No)"

        Dim cmd As New SqlCommand(insQue, con)

        con.Open()

        With cmd

            .Parameters.Add("@Contact_ID", SqlDbType.Int).Value = txtCID.Text.Trim
            .Parameters.Add("@Name", SqlDbType.VarChar).Value = txtName.Text.Trim
            .Parameters.Add("@Address", SqlDbType.VarChar).Value = txtAdd.Text.Trim
            .Parameters.Add("@Cont_No", SqlDbType.VarChar).Value = txtContNum.Text.Trim

        End With

        cmd.ExecuteNonQuery()

        con.Close()
        MessageBox.Show("its inserted")

        If chkShowBusiness.Checked = True Then
            My.Forms.Business_Information.Show()
        End If
    End Sub

和业务信息"表单加载事件代码:

Private Sub Business_Information_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

        Dim con As New SqlConnection(cnStr)
        Dim da As New SqlDataAdapter
        Dim ds As New DataSet

        Dim selQue As String = "Select * from Contact"
        da.SelectCommand = New SqlCommand(selQue, con)

        con.Open()

        da.Fill(ds, "Contact")

        cmbContName.DataSource = ds.Tables("Contact")

        cmbContName.DisplayMember = "Name"
        cmbContName.ValueMember = "Contact_ID"

    End Sub

并保存按钮代码:

Private Sub btnSaveBus_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSaveBus.Click

        Dim con As New SqlConnection(cnStr)
        Dim insQue As String = "Insert into Business_Info (Bus_ID, Contact_ID, Bus_Name, Bus_Loc, Bus_Status) values (@Bus_ID, @Contact_ID, @Bus_Name, @Bus_Loc, @Bus_Status)"

        Dim cmd As New SqlCommand(insQue, con)

        con.Open()

        With cmd
            .Parameters.AddWithValue("@Bus_ID", txtBID.Text.Trim)
            .Parameters.AddWithValue("@Contact_ID", cmbContName.SelectedValue)
            .Parameters.AddWithValue("@Bus_Name", txtBusName.Text.Trim)
            .Parameters.AddWithValue("@Bus_Loc", txtBusLoc.Text.Trim)
            .Parameters.AddWithValue("@Bus_Status", cmbBusStatus.Text)
        End With

        cmd.ExecuteNonQuery()
        con.Close()

        MessageBox.Show("its inserted")
    End Sub

我在互联网上搜索了一些信息，因此发现是在论坛上写的，在一个单独的模块中只能建立一次连接，这与我的代码不同， 我正在为每个代码建立连接.我不知道他们指的是什么，但我推断需要在单独的地方放置通用代码，并在各处使用通用代码?

I was googling some information on internet, so I found that it was written in forums that a connection should be made only once in a separate module not like my code where I am making connection for each code. I don't know what they were referring to but what I inferred that there need to be a separate place where the common code shall be put and used everywhere??

问题

1.我以正确的方式推断出来了吗?

2.我试图做的是添加一个模块内容(我不太了解它的细节)，然后在那儿写了代码.

出于测试目的，我制作了一个模块

For test purpose I made a module

Module modConn

    Public cnStr As String = "Data Source = (local); Initial Catalog = AddressBook; User ID = sa; Password = colrh"

End Module

我不知道如何在单独的地方编写代码，但是我尝试过了，对吗?

I don't know that how to write the code in a separate place but I tried this, Is it right?

 

3.如果我必须在单独的模块中声明整个连接代码，那么我将如何在任何地方使用相同的东西，并且大多数人有必要这样做吗?

谢谢.

推荐答案

也许您应该看看另一幅图片.

Maybe you should look at a different picture.

https://en.wikipedia.org/wiki/关注的问题

https://en.wikipedia.org/wiki/Separation_of_concerns

https://msdn.microsoft.com/zh-CN/library/bb384398.aspx

https://msdn.microsoft.com/en-us/library/bb384398.aspx

http://www.codeproject.com/Articles/21115/Building-an-N-Tier-Application-in-VB-NET-in-Step

http://www.codeproject.com/Articles/21115/Building-an-N-Tier-Application-in-VB-NET-in-Step

http://www.codeproject.com/Articles/228214/Understanding-Basics-of-UI-Design-Pattern-MVC-MVP

http://www.codeproject.com/Articles/228214/Understanding-Basics-of-UI-Design-Pattern-MVC-MVP

您必须使用Bing或Google找到一个VB.NET示例，但使用C#的示例不是这样

You'll have to find a VB.NET example they are out there using Bing or Google, but not at the rate examples are in C#

http://www.codeproject.com/Articles/522809/WinForms-MVP-An-MVP-Framework-for-WinForms

http://www.codeproject.com/Articles/522809/WinForms-MVP-An-MVP-Framework-for-WinForms

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