C＃，ASP.NET-从数据库收集数据

Question

I have code, which returns me a row out of a database,

            con = new System.Data.SqlClient.SqlConnection();
            dsl = new DataSet();
            con.ConnectionString = "Data Source=.\\SQLEXPRESS;AttachDbFilename=C:\\tbl.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True";

            con.Open();

            string sql = "SELECT * From tbl_fb";
            da = new System.Data.SqlClient.SqlDataAdapter(sql, con);
            da.Fill(dsl, "fb");
            DataRow dRow = dsl.Tables["fb"].Rows[0];
            ViewData["a"] = dRow.ItemArray.GetValue(1).ToString();

            ViewData["b"] = "afagjma";
            con.Close();

Is there a way, that I could use a loop to get all rows from table. The number of rows are unknown. I know I can do it with a loop, by using the variable (i) instead of numbers. But then I would need to use the ViewData array, which is problem for me.

Example: ViewData["a"][i];

Answer 1

You should set up a class that defines what data you're returning from your database.

For instance:

public class Customer  
{
   public int Id { get; set;} 
   public string Name { get; set;} 
} 

And then you would create a List<Customer>() , and set this as the Model for your MVC Page.

For instance:

var data = new new List<Customer>();    
ViewData.Model = data; 

And load your data into your list:

foreach(var row in dsl.Tables["fb"].Rows)
{
   var customer = new Customer(); 
   customer.Id = row.Field<int?>("Id"); 
   customer.Name = row.Field<string>("Name");
   data.Add(customer);
}

And then, on your MVC Page, set the <%@ Page %> header to have the Inherits attribute like so:

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<IEnumerable<Customer>>" %>

Now finally you can bind directly to the Model within the page:

<% foreach (var item in Model) { %>
  Customer Id: <%: item.Id %>
  Name: <%: item.Name %>
<% } %>

Answer 2

The simplest way to go through each DataRow in your "fb" table is:

foreach (DataRow dr in dsl.Tables["fb"].Rows) {
    // do something with each row
}

This will run through all rows of your table.

To return a value of a particular column in your DataRow object, do something like this:

string firstName = (string)dr["FirstName"];
string lastName = (string)dr["LastName"];
int age = (int)dr["Age"];

By doing this, you're saying "Get me the value from the 'FirstName' column and cast it as an string, cast the value from the 'Age' column as an integer, and so-on. However you need to verify the type being returned for each column and adjust your casts accordingly.

Answer 3

You need to loop through dsl as this is the dataset. This is your problem:

DataRow dRow = dsl.Tables["fb"].Rows[0];

You are getting a single DataRow Rows[0] where you need to loop through dsl to get each and every DataRow

Answer 4

Why not use a DataReader instead? It would work in a loop reading one row at a time. You can use it to populate a DataTable and pass it on to a DataSet , if needed.