Question

在这里，我使用带有C＃的Windows应用程序创建了一个条形图。我从存储过程中检索数据并绑定条形图。到目前为止，我写了这段代码：

try
        {
            SqlConnection con = new SqlConnection();
            con.ConnectionString = "Data Source=ARUN-PC/SQLEXPRESS;Initial Catalog=InsightPro_Latest ;Integrated Security=True";

            con.Open();


            SqlCommand cmd = new SqlCommand();
            cmd.Connection = con;

            SqlDataAdapter da = new SqlDataAdapter(cmd);
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.CommandText = "SumofPowders";

            DataSet ds = new DataSet();
            da.Fill(ds);
            InsightPro_BarChart.DataSource = ds;
            InsightPro_BarChart.DataBind();
            con.Close();




        }
        catch
        {

        }

现在我遇到了错误：The ConnectionString property has not been initialized。我不知道我在哪里犯了这个错误。

任何人都可以澄清我对编码的疑问吗？提前谢谢。

Answer 1

为SqlConnection提供连接字符串（否则它将不知道连接到哪个数据库）：

string connectionString = "Server=Name;Database=DbName;User=Foo;Password=Bar";
SqlConnection con = new SqlConnection(connectionString);
// you can also set connection string via property
// con.ConnectionString = connectionString;

通常，连接字符串存储在<connectionStrings>部分中应用程序的配置文件中（请参阅Connection Strings and Configuration Files）：

<connectionStrings>
  <add name="myConnection" 
       connectionString="Server=Name;Database=DbName;User=Foo;Password=Bar"
       providerName="System.Data.SqlClient"/>
</connectionStrings>

您可以使用ConfigurationManager从配置文件中获取连接字符串（您应该添加对 System.Configuration 程序集的引用）：

string connectionString =
    ConfigurationManager.ConnectionStrings["myConnection"].ConnectionString;

Answer 2

您需要为SQL添加连接字符串。

例如：

string connectionString = "Server=myServerAddress;Database=myDataBase;User Id=myUsername;
Password=myPassword;";

然后执行所需的SqlConnection：

SqlConnection con = new SqlConnection(connectionString);

有关连接字符串的更多信息：http://www.connectionstrings.com/sql-server-2005/

您可以在配置文件中添加数据库连接详细信息：

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <connectionStrings>
        <add name="Test" connectionString="Data Source=.;Initial Catalog=OmidPayamak;IntegratedSecurity=True" providerName="System.Data.SqlClient" />
    </connectionStrings>
</configuration>

完成配置后，您需要为连接访问相同的配置。您可以使用ConfigurationManager：

using System; 
using System.Configuration;

var connectionString = ConfigurationManager.ConnectionStrings["Test"];

然后使用SqlConnection传递连接并开始：

SqlConnection con = new SqlConnection(connectionString);

Answer 3

试试这个

    SqlConnection conn = new SqlConnection();
    conn.ConnectionString = "Server=myServerAddress;Database=myDataBase;User Id=myUsername;
Password=myPassword";
    conn.Open();

的Web.config

<connectionStrings>
   <add name="ApplicationServices" connectionString="copy connection string here" 
    />
 </connectionStrings>

     SqlCommand command = new SqlCommand();
     command.CommandText = "SumofPowders";
     command.CommandType = CommandType.StoredProcedure;
     con.open();
     SqlDataAdapter da = new SqlDataAdapter(command,con);
     DataSet ds = new DataSet();
     da.Fill(ds);
     InsightPro_BarChart.DataSource = ds;
     InsightPro_BarChart.DataBind();

Answer 4

在webconfig标记内的ConnectionString添加连接字符串

<add name="constr" connectionString="Data Source=ARUN-PC/SQLEXPRESS;Initial Catalog=InsightPro_Latest ;User ID= YourServersername ;Password=YourServerPassword" providerName="System.Data.SqlClient"/>

中的代码

string conn = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
 SqlConnection con = new SqlConnection(conn);

C＃中的条形图

4 个答案: