返回数据表和字符串

Question

我想返回一个应该包含一个字符串的数据表，在返回一个数据表时手动添加一个字符串，下面是我正在使用的代码：

static public DataTable GetInfoByCode(string code, string user)
    {

    string sql =    "SELECT aspnet_Users.UserName,  " +
                    "Code.dateUsed" +
                    "FROM aspnet_Membership INNER JOIN" +
                    "aspnet_Users ON aspnet_Membership.UserId = aspnet_Users.UserId INNER JOIN"+
                    "rAccessCode ON aspnet_Users.UserId = rAccessCode.userID INNER JOIN"+
                    "Code ON rAccessCode.CodeID = Code.accessCodeID"+
                    "WHERE (Code.accessCode = code)";

                    MembershipUser userPass = Membership.GetUser(user);
                    string password = userPass.GetPassword();
                    SqlDataAdapter da = new SqlDataAdapter(sql, ConnectionString);
        DataTable dt = new DataTable();
        da.Fill(dt);
        return dt; //want to return password field in the dt so that i can link datasource with datagridview and show password and username in gridview
        }

我想在 dt 中添加密码，以便在 datagrid 视图中检索密码字段，例如：

<asp:GridView ID="gvList" runat="server" >
    <Columns>
        <asp:BoundField DataField="UserName" ReadOnly="True" HeaderText="Username" />
        <asp:BoundField DataField="password" ReadOnly="True" HeaderText="Password" />
    </Columns>
</asp:GridView>

Answer 1

如果您希望数据表中有一个且只有一行，您可以进行以下修改：

DataTable dt = new DataTable();
da.Fill(dt);
//Add the password column:
dt.Columns.Add("password", typeof (String)); 
//set the value:
dt.Rows[0]["password"] = password;
//Now return your datatable

这将向 DataTable 添加一个名为 password 的附加列，然后您为其设置值。

但是，在您的原始示例中，我看不到您在哪里过滤用户名。像下面这样的查询在这里应该有所帮助：

string sql =    "SELECT aspnet_Users.UserName,  " +
                "Code.dateUsed " +
                "FROM aspnet_Membership INNER JOIN" +
                "aspnet_Users ON aspnet_Membership.UserId = aspnet_Users.UserId INNER JOIN"+
                "rAccessCode ON aspnet_Users.UserId = rAccessCode.userID INNER JOIN"+
                "Code ON rAccessCode.CodeID = Code.accessCodeID"+
                "WHERE (Code.accessCode = @code)";


                using(SqlConnection connection = new SqlConnection("connstring"))
                {
                    using(SqlCommand command = new SqlCommand())
                    {
                        command.Connection = connection;
                        command.CommandType = CommandType.Text;
                        command.Text = sql;

                        command.Parameters.AddWithValue("@code", code);

                        connection.Open();

                        using(SqlDataReader reader = command.ExecuteReader())
                        {
                            dt.Load(reader);
                        }

                    }


                } 

请注意，查询已被参数化，因此我们只尝试返回与用户代码匹配的行。如果不存在这样的行，你会想要满足这个（例如dt.Rows.Count == 0）

但是，我同意其他发帖者的观点，您没有理由不将其表示为自定义用户对象 - 您仍然可以将其数据绑定到显示器。例如：

public class User{

  public string UserName { get; set; }

  public string Code { get; set; }

  public string PasswordHash { get; set; }


  public User()
  {

  }


} 

然后，在加载过程中：

User user = new User();     

using(...)
{
        using(SqlDataReader reader = command.ExecuteReader())
        {
            if(reader.Read())
            {   
                user.UserName = reader.GetString(reader.GetOrdinal("UserName"));
            }     
        }
    }

user.PasswordHash = userPass.GetPassword();
user.Code = code;

其中 using(...) 是外部 using 块的简写。

这也没有理由不能是List<User>。

Answer 2

最好返回包含所有想要的值的对象，然后将数据网格绑定到这些对象的列表。但是，如果您想坚持使用 DataTable 解决方案，您可以添加列（或在下面的示例中添加它以选择）并用密码数据填充它。顺便提一句。似乎此查询将返回只有一行的 DataTable：

static public DataTable GetInfoByCode(string code, string user) {

string sql =    "SELECT aspnet_Users.UserName,  " +
                "Code.dateUsed, Password as '' " +
                "FROM aspnet_Membership INNER JOIN" +
                "aspnet_Users ON aspnet_Membership.UserId = aspnet_Users.UserId INNER JOIN"+
                "rAccessCode ON aspnet_Users.UserId = rAccessCode.userID INNER JOIN"+
                "Code ON rAccessCode.CodeID = Code.accessCodeID"+
                "WHERE (Code.accessCode = code)";

                MembershipUser userPass = Membership.GetUser(user);
                string password = userPass.GetPassword();
                SqlDataAdapter da = new SqlDataAdapter(sql, ConnectionString);
    DataTable dt = new DataTable();
    da.Fill(dt);
    if (dt.Rows.Count > 0)
      dt.Rows[0].SetField<string>("Password", password);
    return dt; //want to return password field in the dt so that i can link datasource with datagridview and show password and username in gridview
    }

Answer 3

如果总是返回一条记录，那么你可以这样做

dt.Columns.Add("Password");
dt.Rows[0]["Password"] = password;

否则您将不得不遍历您的记录并分配密码