如何从 web.config 添加和访问连接字符串

Question

我想添加连接字符串来连接到 web.config 文件中定义的 mysql，并在我的 C# 代码中访问相同的连接，我该怎么做？

这是我的代码示例，在单击按钮连接到数据库后运行。

protected void Button2_Click(object sender, EventArgs e)
    {
        String a = DropDownList1.SelectedItem.Value;
        String b = DropDownList3.SelectedItem.Value.PadLeft(3, '0');      
        String c = TextBox2.Text.PadLeft(5,'0').ToString();
        String d = TextBox3.Text.ToString();
        String digit = a+ b  + c + d;
        try
        {
         myConn = new OdbcConnection("Driver={MySQL ODBC 3.51 Driver};Server=localhost;Database=testcase;User=root;Password=root;Option=3;");
         myConn.Open();
            //**
            string sql = "select * from testcase.main where reg_no =?";            
            //**
            OdbcCommand cmd = new OdbcCommand(sql, myConn);            
            //**
            cmd.Parameters.AddWithValue("?", digit);
            MyReader = cmd.ExecuteReader();
            //**
            while (MyReader.Read())
            {
                String f = MyReader["pet_name"].ToString();
                String g = MyReader["res_name"].ToString();

                Label9.Visible = true;
                Label9.Text = f;

                Label10.Visible = true;
                Label10.Text = "VS";

                //Label11.Visible = true;
                Label11.Text = g;

            }

            MyReader.Close();
        }
        catch (Exception e1)
        {
            Response.Write(e1.ToString());
        }
        finally
        {
            if (MyReader != null && !MyReader.IsClosed)
            {
                MyReader.Close();   
            }

            if (myConn != null && myConn.State == ConnectionState.Open)
            {
                myConn.Close();
            }
        }

Answer 1

在所有这个答案中 static 缺少

导入此命名空间：

using System.Configuration;

获取连接字符串：

static string ConnectionString = ConfigurationManager.ConnectionStrings["ConnectionStringName"].ConnectionString.ToString();

Answer 2

网络配置

<connectionStrings>   
     <add name="cn"connectionString="server=localhost;database=database_name;uid=username;password=your password"/> 
</connectionStrings>

aspx页面

string constr=ConfigurationManager.ConnectionStrings["cn"].ConnectionString;
MySqlConnection con = new MySqlConnection(constr);
MySqlCommand cmd =new MySqlCommand("select * from  tbl_mastercampaign", con);

Answer 3

的 ConnectionStrings 属性

如果您知道连接字符串名称，则可以使用 ConfigurationManager类

using System.Configuration;
string ConnectionString = ConfigurationManager.ConnectionStrings["ConnectionStringName"].ConnectionString.ToString();

其中，您的 web.config 将包含名为 ConnectionStringName 的连接字符串

Answer 4

以下是为 SQL Server 创建连接字符串并将其添加到 web.config 的示例
您可以将 sql 连接更改为 OleDb 连接

SqlConnectionStringBuilder connectionStringBuilder = new SqlConnectionStringBuilder();
        connectionStringBuilder.DataSource = "localhost";
        connectionStringBuilder.IntegratedSecurity = true;
        connectionStringBuilder.InitialCatalog = "SampleDB";

        ConnectionStringSettings connSttng = new ConnectionStringSettings();
        connSttng.Name = "ConnectionStringName";
        connSttng.ProviderName = "Providername";
        connSttng.ConnectionString = String.Format("DataSource={0};InitialCatalog={1};IntegratedSecurity={2}", connectionStringBuilder.DataSource, connectionStringBuilder.InitialCatalog, connectionStringBuilder.IntegratedSecurity);

        Configuration config = WebConfigurationManager.OpenWebConfiguration("~");
        config.ConnectionStrings.ConnectionStrings.Add(connSttng);
        config.Save(ConfigurationSaveMode.Modified, true);
        ConfigurationManager.RefreshSection("connectionStrings");

希望这将是完整的

Answer 5

在网络配置中：

<connectionStrings>
<add 
    name="NorthwindConnectionString"
    connectionString="Data Source=serverName;Initial 
    Catalog=Northwind;Persist Security Info=True;User
    ID=userName;Password=password"
    providerName="System.Data.SqlClient"/>
 </connectionStrings>

在视图中：

using System.Configuration;
string ConnectionString =ConfigurationManager.ConnectionStrings["NorthwindConnectionString"].ConnectionString.ToString();