从 WPF 桌面应用程序中的数据库中检索数据

Question

我是 C# 新手，我刚刚学会了如何在我的 WPF 应用程序中将数据输入到 database.mdf 的数据表中。

这是通过以下代码完成的

SqlConnection sqlCon = new SqlConnection(@"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True;");
try
{
    if (sqlCon.State == ConnectionState.Closed)
        sqlCon.Open();
    String query = "SELECT COUNT(1) FROM tbl WHERE Username=@Username and Password=@Password";
    SqlCommand sqlCmd = new SqlCommand(query, sqlCon);
    sqlCmd.CommandType = CommandType.Text;
    sqlCmd.Parameters.AddWithValue("@Username", txtbxUsername.Text);
    sqlCmd.Parameters.AddWithValue("@Password", pswbxPassword.Password);
    int count = Convert.ToInt32(sqlCmd.ExecuteScalar());
    if (count == 1)
    {
        MessageBox.Show("Login successfully!");

        DetailPage newpage = new DetailPage();
        newpage.Show();
        this.Close();
    }
    else
    {
        MessageBox.Show("Username or password is incorrect");
    }
}
catch (Exception ex)
{
    MessageBox.Show(ex.Message);
}
finally
{
    sqlCon.Close();
}

目前通过登录页面登录后，有一个详细信息页面，我想在其中显示以前保存在我的数据库中的名字、姓氏、年龄等详细信息。请问我可以使用哪些 SqlCommands 从数据库中检索所有这些参数数据？

Answer 1

在你的位置，我会在我的应用程序中添加一个用户类

public class user
{
    public int ID { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string MailAddress{ get; set; }
}


//You can keep your Logged user in a static class


public static class PublicParameters
{ 
  public static User CurrentUser;

  //Define only one connection string in your application.
  public static string ConnectionString= @"Data Source=   (LocalDB)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated 
 Security=True;"
}




    void Login()
    {
        using (SqlConnection sqlConn = new SqlConnection(ConnectionString))
        {
            using (SqlCommand sqlComm = new SqlCommand("SELECT COUNT(1) FROM tbl WHERE Username=@Username AND Password=@Password", sqlConn))
            {
                if (sqlComm.Connection.State == System.Data.ConnectionState.Closed)
                    sqlComm.Connection.Open();
                SqlDataReader sqlRd = sqlComm.ExecuteReader();
                sqlComm.Parameters.AddWithValue("@Username", txtbxUsername.Text);
                sqlComm.Parameters.AddWithValue("@Password", pswbxPassword.Password);

                //Your username column must be unique
                while (sqlRd.Read())
                {
                    PublicParameters.CurrentUser = new Controllers.User();
                    PublicParameters.CurrentUser.FirstName = sqlRd["FirstName"].ToString();
                    PublicParameters.CurrentUser.LastName = sqlRd["LastName"].ToString();
                    PublicParameters.CurrentUser.MailAddress = sqlRd["MailAddress"].ToString();
                    //And other properties to assign
                }

                if(PublicParameters.CurrentUser != null)
                {
                    MessageBox.Show("Login successfully!");
                    //Yo have your logged user 
                }
                else
                {
                    MessageBox.Show("Username or password is incorrect");
                }
            }
        }
    }