如何使用 app.config 从 vb.net 连接到 MySQL 数据库

Question

我需要有关如何转换当前连接并在我的 vb.net 项目中使用 app.config 迁移的帮助，因此当我传输或编辑我的数据库凭据时，我不需要为我的程序重新编译新的安装程序。提前谢谢小伙伴们！

这是我当前的连接：

（我的mdlConnection.vb里面的代码）

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

这是我app.config 中的配置：

Answer 1

在解决方案资源管理器中双击您项目的“我的项目”条目。从打开的窗口转到设置选项卡。将类型更改为连接字符串，如下面的屏幕截图所示

或者，您可以将以下内容添加到您的 app.config 文件中 <configuration> 开始标记下方；

<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 2

这是我的设置

这是我更新的 mdlConnection

这是我更新的 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

Answer 3

请更新您当前的 app.config 文件如下：

    <?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>

然后修改你的'mdlConnection.vb'代码如下：

    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”以及在您的解决方案中引用“System.Configuration”。