How do I connect to a SQL database from C#?

Check out

• Introduction to ADO.NET Tutorial
• ADO.NET Tutorial Lesson 1
• An introduction to ADO.NET

I'm sure there's plenty more out there - just google for "ADO.NET" and "Tutorial" ......

UPDATE:

If you want to connect to your local SQL Server Express, and connect to the "Northwind" database, and read the top 5 customers from the "Customers" table, you'd have to do something like this:

string connectionString = "server=(local)\SQLExpress;database=Northwind;integrated Security=SSPI;";using(SqlConnection _con = new SqlConnection(connectionString)){   string queryStatement = "SELECT TOP 5 * FROM dbo.Customers ORDER BY CustomerID";   using(SqlCommand _cmd = new SqlCommand(queryStatement, _con))   {      DataTable customerTable = new DataTable("Top5Customers");      SqlDataAdapter _dap = new SqlDataAdapter(_cmd);      _con.Open();      _dap.Fill(customerTable);      _con.Close();   }}

Now you would have all 5 top customers from your Northwind database in the DataTable and you can inspect them, print them out, manipulate them - whatever you want to do.

That's ADO.NET in action!

As for the details of the connection string - what options you can use and what it should look like, check out the Connection Strings web site - it has tons of examples and explanations.

Marc

SqlConnection

object is made for this.

Eg:

SqlConnection conn = new SqlConnection(    "Data Source=(local);Initial Catalog=Northwind;Integrated Security=SSPI"); 

or

SqlConnection conn = new SqlConnection("Data Source=DatabaseServer; Initial Catalog=Northwind; User ID=YourUserID; Password=YourPassword");conn.Open(); // opens the database connection

Edit:

After doing all your stuff you have to close the connection by

conn.Close();

Data Source: Identifies the server. Could be local machine, machine domain name, or IP Address.

Initial Catalog: Database name.

Integrated Security: Set to SSPI to make connection with user's Windows login

User ID: Name of user configured in SQL Server.

Password: Password matching SQL Server User ID.

To connect to SQL Server Express you need nothing but System.Data, which is a standard .NET assembly. Just use SqlXXX classes and you'll be done.

However, writing mundane ADO.NET code is very boring, so it's very common to use an ORM or less heavy-weight result-set mapper such as BLToolkit.

And finally, consider using SQL Server CE. This is a fully ACID-compliant single-file embedded database engine which supports pretty much any feature you can expect form an SQL RDBMS.