в 15:30, 26 мая 2010

2010-05-26T15:30:57Z

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2010-05-26T11:56:58Z

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== Create DataReader object from SqlCommand==



<source lang="csharp">
<%@ Page Language="C#" %>
<%@ import Namespace="System.Data" %>
<%@ import Namespace="System.Data.SqlClient" %>
<script runat="server">
void Page_Load(object sender, EventArgs e)
{
string ConnectionString = Convert.ToString(ConfigurationSettings.AppSettings["MSDEConnectString"]);

string CommandText = "SELECT AuthorName, AuthorCity, AuthorContact_Email, AuthorWebsite FROM Author";

SqlConnection myConnection = new SqlConnection(ConnectionString);
SqlCommand myCommand = new SqlCommand(CommandText, myConnection);

try
{
myConnection.Open();

SqlDataReader myReader = myCommand.ExecuteReader();
while (myReader.Read()){
Author p = new Author();
p.Name = myReader.GetString(0);
p.City = myReader.GetString(1);
p.Email = myReader.GetString(2);
p.Website = myReader.GetString(3);

Label1.Text += p.ToString();
}

myReader.Close();
} catch (Exception ex)
{
throw (ex);
}
finally
{
myConnection.Close();
}
}

public class Author
{
public string Name;
public string City;
public string Email;
public string Website;

public Author()
{}

public string ToString()
{
string description = "";
description = "Name : " + this.Name + "<br />";
description += "City : " + this.City + "<br />";
description += "Contact : <a href=mailto:" + this.Email + ">" + this.Email + "</a><br/>";
description += "Homesite : <a href="" + this.Website + "">" + this.Website + "</a><br/><br/>";

return description;
}
}
</script>
<html>
<body>
<asp:Label id="Label1" runat="server"></asp:Label>
</body>
</html>
File: Web.config
<configuration>
<appSettings>
<add key="MSDEConnectString"
value="server=(local)\YourDatabase;database=Books;uid=YourID;pwd=letmein;" />

</appSettings>
</configuration></source>

== Iterating Through A DataReader==



<source lang="csharp">
<%@ Page Language="C#" %>
<%@ import Namespace="System.Data" %>
<%@ import Namespace="System.Data.SqlClient" %>
<script runat="server">
void Page_Load(object sender, EventArgs e)
{
string ConnectionString = Convert.ToString(ConfigurationSettings.AppSettings["MSDEConnectString"]);
string CommandText = "SELECT AuthorName, AuthorCity, AuthorContact_Email, AuthorWebsite FROM Author";

SqlConnection myConnection = new SqlConnection(ConnectionString);
SqlCommand myCommand = new SqlCommand(CommandText, myConnection);

try
{
myConnection.Open();
SqlDataReader myReader = myCommand.ExecuteReader();
if (myReader.HasRows)
{
while (myReader.Read())
{
for (int i=0; i<=myReader.FieldCount-1; i++)
{
if (myReader.IsDBNull(i))
{
Label1.Text += "Warning: Field " + i + " is NULL.";
}
}
Author p = new Author();
p.Name = myReader.GetString(0);
p.City = myReader.GetString(1);
p.Email = myReader.GetString(2);
p.Website = myReader.GetString(3);
Label1.Text += p.ToString();
}
}
else
{
Label1.Text = "No rows returned";
}

if(!(myReader.IsClosed))
{
myReader.Close();
}
} catch (Exception ex) {
throw (ex);
} finally {
myConnection.Close();
}
}

public class Author
{
public string Name;
public string City;
public string Email;
public string Website;

public Author()
{}

public string ToString()
{
string description = "";
description = "Name : " + this.Name + "<br />";
description += "City : " + this.City + "<br />";
description += "Contact : <a href=mailto:" + this.Email + ">" + this.Email + "</a><br/>";
description += "Homesite : <a href="" + this.Website + "">" + this.Website + "</a><br/><br/>";

return description;
}
}
</script>
<html>
<body>
<asp:Label id="Label1" runat="server"></asp:Label>
</body>
</html>
File: Web.config
<configuration>
<appSettings>
<add key="MSDEConnectString" value="server=(local)\YourDatabase;database=Books;uid=YourID;pwd=letmein;" />
</appSettings>
</configuration></source>

== List Binding DataReader==



<source lang="csharp">
<%@ Page Language="C#" %>
<%@ import Namespace="System.Data" %>
<%@ import Namespace="System.Data.SqlClient" %>
<script runat="server">
SqlDataReader myReader;

void Page_Load(object sender, EventArgs e)
{
string ConnectionString = Convert.ToString(ConfigurationSettings.AppSettings["MSDEConnectString"]);
string CommandText = "SELECT PublisherID, PublisherName FROM Publisher";

SqlConnection myConnection = new SqlConnection(ConnectionString);
SqlCommand myCommand = new SqlCommand(CommandText, myConnection);

try
{
myConnection.Open();

myReader = myCommand.ExecuteReader();

ListBox1.DataBind();
myReader.Close();
}catch (Exception ex) {
throw (ex);
} finally {
myConnection.Close();
}
}
</script>
<html>
<head>
</head>
<body>
<form runat="server">
<h1>Pulling Values From Data Bound Lists 
</h1>
<h2>A CheckBoxList
</h2>

<asp:CheckBoxList id="CheckBoxList1" runat="server" BorderWidth="2px" BorderStyle="Dotted" DataValueField="PublisherID" DataTextField="PublisherName" DataSource="<%# myReader %>"></asp:CheckBoxList>

<h2>A RadioButtonList
</h2>

<asp:RadioButtonList id="RadioButtonList1" runat="server" DataValueField="PublisherID" DataTextField="PublisherName" DataSource="<%# myReader %>"></asp:RadioButtonList>

<h2>A DropDownList
</h2>

<asp:DropDownList id="DropDownList1" runat="server" DataValueField="PublisherID" DataTextField="PublisherName" DataSource="<%# myReader %>"></asp:DropDownList>

<h2>A ListBox
</h2>

<asp:ListBox id="ListBox1" runat="server" DataValueField="PublisherID" DataTextField="PublisherName" DataSource="<%# myReader %>" Rows="5"></asp:ListBox>

</form>
</body>
</html>

File: Web.config
<configuration>
<appSettings>
<add key="MSDEConnectString" value="server=(local)\YourDatabase;database=Books;uid=YourID;pwd=letmein;" />
</appSettings>
</configuration></source>

== Returning Multiple Resultsets==



<source lang="csharp">
File: App_Code\DataLayer1.cs
using System;
using System.Data;
using System.Data.SqlClient;
using System.Web.Configuration;
using System.Collections.Generic;
public class DataLayer1
{
private static readonly string _connectionString;
public class ProductCategory
{
private int _id;
private string _name; public int Id
{
get { return _id; }
set { _id = value; }
}
public string Name
{
get { return _name; }
set { _name = value; }
}
}
public class Product
{
private string _title;
private int _categoryId;
public string Title
{
get { return _title; }
set { _title = value; }
}
public int CategoryId
{
get { return _categoryId; }
set { _categoryId = value; }
}
}
public static void GetProductData(List<DataLayer1.ProductCategory> productCategories, List<DataLayer1.Product> products)
{
string commandText = "SELECT Id,Name FROM ProductCategories;SELECT Title, CategoryId FROM Products";
SqlConnection con = new SqlConnection(_connectionString);
SqlCommand cmd = new SqlCommand(commandText, con);
using (con)
{
con.Open();
SqlDataReader reader = cmd.ExecuteReader();
while (reader.Read())
{
DataLayer1.ProductCategory newCategory = new DataLayer1.ProductCategory();
newCategory.Id = (int)reader["Id"];
newCategory.Name = (string)reader["Name"];
productCategories.Add(newCategory);
}
reader.NextResult();
while (reader.Read())
{
DataLayer1.Product newProduct = new DataLayer1.Product();
newProduct.Title = (string)reader["Title"];
newProduct.CategoryId = (int)reader["CategoryID"];
products.Add(newProduct);
}
}
}
static DataLayer1()
{
_connectionString = WebConfigurationManager.ConnectionStrings["Products"].ConnectionString;
}
}

File: Web.config
<configuration>
<connectionStrings>
<add name="Products"
connectionString="Data Source=.\SQLEXPRESS;
AttachDbFilename=|DataDirectory|MyDatabase.mdf;Integrated Security=True;User Instance=True" />
</connectionStrings>
</configuration>
File: ShowDataLayer1.aspx
<%@ Page Language="C#" %>
<%@ Import Namespace="System.Collections.Generic" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
void Page_Load()
{
List<DataLayer1.ProductCategory> categories = new List<DataLayer1.ProductCategory>();
List<DataLayer1.Product> products = new List<DataLayer1.Product>();
DataLayer1.GetProductData(categories, products);
grdCategories.DataSource = categories;
grdCategories.DataBind();
grdProducts.DataSource = products;
grdProducts.DataBind();
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>Show DataLayer1</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<h1>Product Categories</h1>
<asp:GridView
id="grdCategories"
Runat="server" />
<h1>Products</h1>
<asp:GridView
id="grdProducts"
Runat="server" />
</div>
</form>
</body>
</html></source>

== Using the DataReader Object==



<source lang="csharp">
DataReader represents the results of a database query.
You get a DataReader by calling a Command object"s ExecuteReader() method.
Verify whether a DataReader has any rows by checking the HasRows property or calling the Read() method.
The DataReader represents a single row of data at a time.
To get the next row of data, you need to call the Read() method.
When you get to the last row, the Read() method returns False.</source>

== Working with Multiple Active Resultsets==



<source lang="csharp">
File: ShowMARS.aspx

<%@ Page Language="C#" %>
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
void Page_Load()
{
if (!Page.IsPostBack)
BuildTree();
}
void BuildTree()
{
string connectionString = @"MultipleActiveResultSets=True;"
+ @"Data Source=.\SQLExpress;Integrated Security=True;"
+ @"AttachDBFileName=|DataDirectory|MyDatabase.mdf;User Instance=True";
SqlConnection con = new SqlConnection(connectionString);
string cmdCategoriesText = "SELECT Id,Name FROM ProductCategories";
SqlCommand cmdCategories = new SqlCommand(cmdCategoriesText, con);
string cmdProductsText = "SELECT Title FROM Products "
+ "WHERE CategoryId=@CategoryID";
SqlCommand cmdProducts = new SqlCommand(cmdProductsText, con);
cmdProducts.Parameters.Add("@CategoryId", SqlDbType.Int);
using (con)
{
con.Open();
SqlDataReader categories = cmdCategories.ExecuteReader();
while (categories.Read())
{
int id = categories.GetInt32(0);
string name = categories.GetString(1);
TreeNode catNode = new TreeNode(name);
TreeView1.Nodes.Add(catNode);
cmdProducts.Parameters["@CategoryId"].Value = id;
SqlDataReader products = cmdProducts.ExecuteReader();
while (products.Read())
{
string title = products.GetString(0);
TreeNode productNode = new TreeNode(title);
catNode.ChildNodes.Add(productNode);
}
products.Close();
}
}
}
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
<head id="Head1" runat="server">
<title>Show MARS</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:TreeView
id="TreeView1"
Runat="server" />
</div>
</form>
</body>
</html></source>

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ASP.NET Tutorial/ADO.net Database/DataReader - История изменений

в 15:30, 26 мая 2010

Admin: 1 версия