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

1. Namespace test
2. {
3. Public partial class _ Default: System. Web. UI. Page
4. {
5. Protected void Page_Load (object sender, EventArgs e)
6. {
7. If (! IsPostBack)
8. {
9. Bind ();
10. }
11. }
13. Private void Bind ()
14. {
15. UserDataContext db = new UserDataContext (); // it is essential to create a DataContext class object.
16. Var user = from u in db. MyUser // rename it as MyUser above. The original table name is User
17. Select u; // the query here is similar to SQL
18. GridView1.DataSource = user; // bind the data source
20. GridView1.DataBind ();
21. }
23. // Insert information
25. Protected void btnAdd_Click (object sender, EventArgs e)
26. {
27. UserDataContext db = new UserDataContext ();
28. String userName = TextBox1.Text;
29. String userPwd = TextBox2.Text;
30. // Db. MyUser. InsertOnSubmit (new MyUser {Name = userName, Pwd = userPwd });
32. // Both the above sentence and the following sentence can be implemented, but they are two different methods.
33. Var user = new MyUser {Name = userName, Pwd = userPwd };
34. Db. MyUser. InsertOnSubmit (user); // execute insert
35. Db. SubmitChanges (); // submit changes to the database
36. Bind ();
37. }

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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.

1. // Delete information
3. Protected void btnDel_Click (object sender, EventArgs e)
4. {
5. UserDataContext db = new UserDataContext ();
6. Int I = Convert. ToInt32 (TextBox3.Text. Trim ());
7. Var user = db. MyUser. First (p => p. Id. Equals (I ));
8. Db. MyUser. DeleteOnSubmit (user );
9. Db. SubmitChanges ();
10. Bind ();
11. }
13. // Update information
15. Protected void btnUpd_Click (object sender, EventArgs e)
16. {
17. UserDataContext db = new UserDataContext ();
18. Int I = Convert. ToInt32 (TextBox3.Text. Trim ());
19. Var user = db. MyUser. First (p => p. Id. Equals (I ));
20. User. Pwd + = user. Pwd;
21. Db. SubmitChanges ();
22. Bind ();
23. }
25. }
26. }

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* 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. (