How to Create a Connection Between C# and SQL Server

[TheReaper989]

In this tutorial, I will teach you how to create a connection between C#.net and SQL Server 2005 Express Edition. In this method, you can access the database that you have created in the SQL Server 2005 Express Edition wherein, you can select the tables and retrieve the data of it.break

In here, we will use Microsoft Visual Basic Studio 2008 for creating this project.

Let's get started:

Create a databaase and name it "dbtest".

Now, open Microsoft Visual Studio 2008 and create a new project.

After that, a “New Project” window will appear. Then, select “Visual C#” and create a new Windows Form Application and hit ok.

After creating a new Windows Form Application, do the Form just like this.

Double click the "Connect Me" button and do the following codes to establish the connection between SQL Server 2005 and C#.Net.

Note: Put using System.Data.SqlClient; above the namespace to access sql server library and to avoid any errors.

1. private
   
   void
   
   button1_Click(
   
   object
   
   sender, EventArgs e)
   
2. {
   
3. //initialize sql connection
   
4. SqlConnection con =
   
   new
   
   SqlConnection(
   
   )
   
   ;
   
5. //set a connection string
   
6. con.
   
   ConnectionString
   
   =
   
   "Data Source=.\\
   
   SQLEXPRESS;Database=dbtest;trusted_connection=true;"
   
   ;
   
7. 
   
8. //opening connection
   
9. con.
   
   Open
   
   (
   
   )
   
   ;
   
10. //validating connection
    
11. 
    
12. if
    
    (
    
    con.
    
    State
    
    ==
    
    ConnectionState.
    
    Open
    
    )
    
13. {
    
14. if
    
    (
    
    button1.
    
    Text
    
    ==
    
    "Connect Me"
    
    )
    
15. {
    
16. button1.
    
    Text
    
    =
    
    "Disconnect Me"
    
    ;
    
17. label2.
    
    Text
    
    =
    
    "Connected"
    
    ;
    
18. }
    
19. else
    
20. {
    
21. button1.
    
    Text
    
    =
    
    "Connect Me"
    
    ;
    
22. label2.
    
    Text
    
    =
    
    "Disconnected"
    
    ;
    
23. con.
    
    Close
    
    (
    
    )
    
    ;
    
24. }
    
25. 
    
26. }
    
27. 
    
28. }
    

Output :

Here is another example that you can also perform.

1. private
   
   void
   
   button1_Click(
   
   object
   
   sender, EventArgs e)
   
2. {
   
3. //initialize sql connection
   
4. SqlConnection con =
   
   new
   
   SqlConnection(
   
   )
   
   ;
   
5. //set a connection string
   
6. con.
   
   ConnectionString
   
   =
   
   "Server=.\\
   
   SQLEXPRESS;"
   
   +
   
7. "User Instance=true;"
   
   +
   
8. "Integrated Security=true;"
   
   +
   
9. "AttachDbFilename="
   
   +
   
   Application.
   
   StartupPath
   
   +
   
   "\\
   
   dbtest.mdf;"
   
   ;
   
10. 
    
11. 
    
12. 
    
13. 
    
14. //opening connection
    
15. con.
    
    Open
    
    (
    
    )
    
    ;
    
16. //validating connection
    
17. 
    
18. if
    
    (
    
    con.
    
    State
    
    ==
    
    ConnectionState.
    
    Open
    
    )
    
19. {
    
20. if
    
    (
    
    button1.
    
    Text
    
    ==
    
    "Connect Me"
    
    )
    
21. {
    
22. button1.
    
    Text
    
    =
    
    "Disconnect Me"
    
    ;
    
23. label2.
    
    Text
    
    =
    
    "Connected"
    
    ;
    
24. }
    
25. else
    
26. {
    
27. button1.
    
    Text
    
    =
    
    "Connect Me"
    
    ;
    
28. label2.
    
    Text
    
    =
    
    "Disconnected"
    
    ;
    
29. con.
    
    Close
    
    (
    
    )
    
    ;
    
30. }
    
31. 
    
32. }
    
33. 
    
34. }
    

Reminder:To make the second option work, you are required to put the database file(dbtest.mdf) inside the bin folder of your project.

Output :

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