如何从vb.net使用的app.config

Question

我需要怎么我的当前连接转换，并在我的vb.net项目中使用app.config所以当我转移迁移或修改数据库证书我不帮助连接到MySQL数据库我需要为我的程序重新编译新的安装程序。在此先感谢队友！

这里是我当前的连接：

Module mdlConnection 
    Public connString1 As String = "server=localhost;user id=root;password=;Database=sampleprog" 
    Public conn As MySqlConnection = New MySqlConnection(connString1) 
    Public sql As String = "" 

    Public Function ExecuteQuery(ByVal query As String) As DataTable 
     Dim sqlDT As New DataTable 
     Try 
      Dim sqlCon As New MySqlConnection(connString1) 
      Dim sqlDA As New MySqlDataAdapter(query, sqlCon) 
      Dim sqlCB As New MySqlCommandBuilder(sqlDA) 
      sqlDA.Fill(sqlDT) 
     Catch ex As Exception 
     End Try 
     Return sqlDT 
    End Function 
End Module 

（在我的mdlConnection.vb代码）这是我的app.config里面的配置：

Answer 1

请如下更新当前的app.config文件：

<?xml version="1.0" encoding="utf-8"?> 
    <configuration> 
     <startup> 
      <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5"/> 
     </startup> 

     <connectionStrings> 
      <add name="MySqlConnectionString" connectionString="SERVER=localhost;DATABASE=sampleprog;UID=root;PASSWORD=;" /> 
     </connectionStrings> 

    </configuration> 

然后如下修改 'mdlConnection.vb' 代码：

Module mdlConnection 
     Public connString1 As String = ConfigurationManager.ConnectionStrings("MySqlConnectionString").ToString() 
     Public conn As MySqlConnection = New MySqlConnection(connString1) 
     Public sql As String = "" 

     Public Function ExecuteQuery(ByVal query As String) As DataTable 
      Dim sqlDT As New DataTable 
      Try 
       Dim sqlCon As New MySqlConnection(connString1) 
       Dim sqlDA As New MySqlDataAdapter(query, sqlCon) 
       Dim sqlCB As New MySqlCommandBuilder(sqlDA) 
       sqlDA.Fill(sqlDT) 
      Catch ex As Exception 
      End Try 
      Return sqlDT 
     End Function 
    End Module 

请不要忘记在您的'mdlConnection.vb'中添加命名空间'Imports System.Configuration'，并在您的解决方案中添加参考'System.Configuration'。

Answer 2

双击项目的“我的项目“在解决方案资源管理器中输入从打开的窗口转到设置选项卡。将类型更改为连接字符串显示在下面的截图

或者，你可以添加以下到<configuration>打开标签下方的app.config文件;

<configuration> 
    <connectionStrings> 
     <add name="<Desired name here>" connectionString="server=localhost;user id=root;password=;Database=sampleprog" /> 
    </connectionStrings> 
    <startup> 
    ... 
</configuration> 

然后，您可以在代码中访问连接字符串，如下所示。

Dim con = My.Settings.DbConnection ' provided you named your connection string DbConnection in the first step above. 

Answer 3

这里是我的设置

这里是我的更新mdlConnection

这里是我的更新mdlConnection

Dim con = My.Settings.DbConnection 
Public conn As MySqlConnection = New MySqlConnection(con) 
Public sql As String = "" 

Public Function ExecuteQuery(ByVal query As String) As DataTable 
    Dim sqlDT As New DataTable 
    Try 
     Dim sqlCon As New MySqlConnection(con) 
     Dim sqlDA As New MySqlDataAdapter(query, sqlCon) 
     Dim sqlCB As New MySqlCommandBuilder(sqlDA) 
     sqlDA.Fill(sqlDT) 
    Catch ex As Exception 
    End Try 
    Return sqlDT 
End Function