ASP. NET uses LINQ to SQL to implement basic addition, deletion, modification, query, and binding controls (C #)

Just a little bit of LINQ was attracted by it, and I suddenly came up with the idea of learning and using it in one breath. So I posted a video on the ASP. NET official website. I am not very good at English, but I can understand how to use it. Below I wrote a little bit of fur I learned. It is a learning record.

First, I use Visual Studio 2008 development tools and SQL server data sources, which are written in C.

Step 1: Create an SQL Server Data Source

Create a database first

　　　　

Another user table is created.

　　　　

I believe these are all pediatric things, so I will not talk about them any more.

Step 2: Add a LINQ to SQL class

I created a user. dbml LINQ to SQL class.

　　　　

Drag the table from the server resource manager to the view. You can double-click the table title in the view to rename it.

　　　　

Save it.

Step 3: Create and execute a query

Namespace Test
{
Public partial class _ default: system. Web. UI. Page
{
Protected void page_load (Object sender, eventargs E)
{
If (! Ispostback)
{
BIND ();
}
}

Private void BIND ()
{
Userdatacontext DB = new userdatacontext (); // it is essential to create a datacontext class object.
VaR user = from u in db. myuser // rename it as myuser above. The original table name is user
Select U; // the query here is similar to SQL
Gridview1.datasource = user; // bind the data source

Gridview1.databind ();
}

// Insert information

Protected void btnadd_click (Object sender, eventargs E)
{
Userdatacontext DB = new userdatacontext ();
String username = textbox1.text;
String userpwd = textbox2.text;
// DB. myuser. insertonsubmit (New myuser {name = username, Pwd = userpwd });

// Both the above sentence and the following sentence can be implemented, but they are two different methods.
VaR user = new myuser {name = username, Pwd = userpwd };
DB. myuser. insertonsubmit (User); // execute insert
DB. submitchanges (); // submit changes to the database
BIND ();
}

The subsequent deletion and update operations are similar to the preceding insert operations, but the query and execution methods are different. The most important part is how to create a query. Later, we will provide you with some keywords for querying basic operations in LINQ. How to use these keywords remains to be learned in the future.

// Delete information

Protected void btndel_click (Object sender, eventargs E)
{
Userdatacontext DB = new userdatacontext ();
Int I = convert. toint32 (textbox3.text. Trim ());
VaR user = dB. myuser. First (P => P. Id. Equals (I ));
DB. myuser. deleteonsubmit (User );
DB. submitchanges ();
BIND ();
}

// Update information

Protected void btnupd_click (Object sender, eventargs E)
{
Userdatacontext DB = new userdatacontext ();
Int I = convert. toint32 (textbox3.text. Trim ());
VaR user = dB. myuser. First (P => P. Id. Equals (I ));
User. pwd + = user. pwd;
DB. submitchanges ();
BIND ();
}

}
}

 

* Query the keywords of basic operations in LINQ

-- From clause

-- Where clause

-- Select clause

-- Group clause

-- Into clause

-- Orderby clause

-- Join clause

-- Let clause

The above is a small article I first learned about LINQ. It may not be easy to understand. Please forgive me. If there is any error, please leave a message to me.