Add, query, update, and delete objects in. Net 3.5-dlinq (LINQ to SQL)

Step by step vs 2008 +. Net 3.5 (8)-add, query, update, and delete Object-oriented Data in dlinq to SQL

Author: webabcd

Introduction
Taking northwind as an example database, dlinq (LINQ to SQL) fully object-oriented addition, query, update, and deletion operations

Example
Sample. aspx

<% @ Page Language = "C #" masterpagefile = "~ /Site. Master "autoeventwireup =" true "codefile =" sample. aspx. cs"
Inherits = "linq_dlinq_sample" Title = "Object-Oriented addition, query, update, and deletion" %>

<Asp: Content ID = "content1" contentplaceholderid = "head" runat = "server">
</ASP: content>
<Asp: Content ID = "content2" contentplaceholderid = "contentplaceholder1" runat = "server">
<P>
Category name: <asp: textbox id = "txtcategoryname" runat = "server"> </ASP: textbox>
Category Description: <asp: textbox id = "txtdescription" runat = "server"> </ASP: textbox>

<Asp: button id = "btnadd" runat = "server" text = "add" onclick = "btnadd_click"/>
</P>
<Asp: gridview id = "gvcategory" runat = "server" datakeynames = "categoryid" onselectedindexchanged = "gvcategory_selectedindexchanged"
Onrowdeleting = "gvcategory_rowdeleting" onrowcancelingedit = "gvcategory_rowcancelingedit"
Onrowediting = "gvcategory_rowediting" onrowupdating = "gvcategory_rowupdating">
<Columns>
<Asp: commandfield showselectbutton = "true" showeditbutton = "true" showdeletebutton = "true">
</ASP: commandfield>
</Columns>
</ASP: gridview>
<Br/>
<Asp: detailsview id = "dvproduct" runat = "server" datakeynames = "productid">
</ASP: detailsview>
</ASP: content>

Sample. aspx. csusing system;
Using system. Data;
Using system. configuration;
Using system. collections;
Using system. LINQ;
Using system. Web;
Using system. Web. Security;
Using system. Web. UI;
Using system. Web. UI. webcontrols;
Using system. Web. UI. webcontrols. webparts;
Using system. Web. UI. htmlcontrols;
Using system. xml. LINQ;

Using Dal;

Public partial class linq_dlinq_sample: system. Web. UI. Page
{
// Instantiate a northwinddatacontext (datacontext)
Northwinddatacontext _ CTX = new northwinddatacontext ();

Protected void page_load (Object sender, eventargs E)
{
If (! Page. ispostback)
{
Bindcategory ();
}
}

Private void bindcategory ()
{
// The category attribute of the northwinddatacontext object is the category set.
VaR categories = _ CTX. categories;

Gvcategory. datasource = categories;
Gvcategory. databind ();
}

Protected void btnadd_click (Object sender, eventargs E)
{
// Instantiate a category
Categories c = new categories ();

// Set attributes of the category object
C. categoryname = txtcategoryname. text;
C. Description = txtdescription. text;

// Use the insertonsubmit () method of the northwinddatacontext object to add a category object
_ CTX. categories. insertonsubmit (C );

// Generate and execute the corresponding SQL command
_ CTX. submitchanges ();

Gvcategory. editindex =-1;
Bindcategory ();
}

Protected void gvcategory_selectedindexchanged (Object sender, eventargs E)
{
// Use the query syntax to obtain the product set
VaR products = from P in _ CTX. Products
Where p. categories. categoryid = (INT) gvcategory. selectedvalue
Select P;

Dvproduct. datasource = products;
Dvproduct. databind ();
}

Protected void gvcategory_rowdeleting (Object sender, gridviewdeleteeventargs E)
{
// Use the single query operator to obtain the specified category object
Categories category = _ CTX. categories. Single (C => C. categoryid = (INT) gvcategory. datakeys [E. rowindex]. value );

// Use deleteonsubmit () to delete the specified category object in the category set of the northwinddatacontext object
_ CTX. categories. deleteonsubmit (category );

// Generate and execute the corresponding SQL command
_ CTX. submitchanges ();

Gvcategory. editindex =-1;
Bindcategory ();
}

Protected void gvcategory_rowupdating (Object sender, gridviewupdateeventargs E)
{
// Use the query syntax and single query operator to obtain the specified category object
Categories category = (from C in _ CTX. Categories
Where C. categoryid = (INT) gvcategory. datakeys [E. rowindex]. Value
Select c). Single ();

// Set attributes of the category object
Category. categoryname = (textbox) gvcategory. Rows [E. rowindex]. cells [2]. controls [0]). text;
Category. Description = (textbox) gvcategory. Rows [E. rowindex]. cells [3]. controls [0]). text;

// Generate and execute the corresponding SQL command
_ CTX. submitchanges ();

Gvcategory. editindex =-1;
Bindcategory ();
}

Protected void gvcategory_rowediting (Object sender, gridviewediteventargs E)
{
Gvcategory. editindex = E. neweditindex;
Bindcategory ();
}

Protected void gvcategory_rowcancelingedit (Object sender, gridviewcancelediteventargs E)
{
Gvcategory. editindex =-1;
Bindcategory ();
}
}

OK
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