Easily Connect to a Database In C#

Now the screen for Add Connection appears. Here we select our database file from where we save it.

Select your database file from your computer drive and click on "Open".

Now to check whether our connection is successful or not. Click On "Test Connection". Now click on "OK" to close the test connection message box.

After that click on the "Add Connection's 'OK' button to complete our database add operation".

Now see in Server Explorer. Here you will see the database and its fields in "Data Connection" as in the following.

Now right-click on the database name (i.e. data. accdb) and select Properties (Alt+Enter).

It opens a "Properties" sidebar. Click on the Connection String and copy that. We need it for our connection coding.

Now We Start Our Code

First of all, take two textbox fields and one button.

Text Box 1	txt_user	for username
Text Box 2	txt_pass	for password
Button 1	btn_ok	for submit

Add References

using System.Data.OleDb.
Now for the button's Click Event (for that double-click on the "OK" button) place this code.
string str = "";
// Paste your connection string that you copy from your database Properties.OleDbConnection con = new OleDbConnection(str);
OleDbCommand cmd =new OleDbCommand("SELECT COUNT(*) FROM tablename WHERE user = '" + txt_user.text +"' AND pass = '" + txt_pass.text +"'", con);
con.Open();try{int i;
i =Convert.ToInt32(cmd.ExecuteScaler());
if (i == 1){MessageBox.Show("Success");
}
else{MessageBox.Show("Invalid User Name or Password");
}
}
Catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
Finaly
{
Con.Close();
}

You can also perform "Insert", "Delete", "Update" etc. operations using this code. For that just change the query and replace "Ex ecuteNonQuery()" with "Ex ecuteSca ler()".