Null连接-正在连接到ASP.NET-Microsoft SQL Server

本文关键字：连接 NET-Microsoft SQL Server ASP Null | 更新日期: 2023-09-27 18:20:19

我一直在尝试连接到数据库，但它显示"null"错误。所以我试着打开我练习的前一个表格，结果非常好。

这是我的代码：

string username = txtusername.Text;
        string firstname = txtfirstname.Text;
        string lastname = txtlastname.Text;
        string email = txtemail.Text;
        string password = txtpass.Text;
        string gender = rbgender.Text;
        string nationality = dcountry.Text;
        string phone = txtphone.Text;
        string connection = ConfigurationManager.ConnectionStrings["connectionString"].ConnectionString;
        SqlConnection connect = new SqlConnection(connection);
        string command = "INSERT INTO Persons(username, firstname, lastname, email, password, gender, nationality, phone) VALUES('@username','@firstname','@lastname','@email','@password','@gender','@nationality','@phone')";

        SqlCommand insert = new SqlCommand(command +","+ connection);
        insert.Parameters.AddWithValue("@username", username);
        insert.Parameters.AddWithValue("@firstname", firstname);
        insert.Parameters.AddWithValue("@lastname", lastname);
        insert.Parameters.AddWithValue("@email", email);
        insert.Parameters.AddWithValue("@password", password);
        insert.Parameters.AddWithValue("@gender", gender);
        insert.Parameters.AddWithValue("@nationality", nationality);
        insert.Parameters.AddWithValue("@phone", phone);
        insert.ExecuteNonQuery();
        connect.Close();

它与web.config中的连接字符串有关吗？

 <connectionStrings>
<add name="ApplicationServices"
     connectionString="Data Source=ADRIAN-LAPTOP'SQL;Initial Catalog=New;Integrated Security=True"
     providerName="System.Data.SqlClient" />

Null连接-正在连接到ASP.NET-Microsoft SQL Server

web.config文件中的键与代码中使用的键不同。

应该是

string connection = ConfigurationManager.ConnectionStrings["ApplicationServices"]
                                        .ConnectionString;

并且不需要将参数名称包装在单引号中。

 string command = @"
   INSERT INTO Persons
      (username, firstname, lastname, email, password, gender, nationality,phone) 
     VALUES
      (@username,@firstname,@lastname,@email,@password,@gender,@nationality,@phone)";

附带说明一下，总是使用using语句（或调用Dispose()）来处理ADO资源。

using(SqlConnection connect = new SqlConnection(connectionString))
 {
  //
 }
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