1.直接写数据库连接字符串

string constr = "server=.;database=myschool;integrated security=SSPI";//string constr = "server=.;database=myschool;uid=sa;pwd=sa";//string constr = "data source=.;initial catalog=myschool;user id=sa;pwd=sa";SqlConnection con = new SqlConnection(constr);// con.ConnectionString = constr;string sql = "select count(*) from grade";SqlCommand com = new SqlCommand(sql,con);try{      con.Open();      MessageBox.Show("成功连接数据库");      int x = (int)com.ExecuteScalar();      MessageBox.Show(string.Format("成功读取{0},条记录", x));}catch (Exception){      throw;}finally{      con.Close();      MessageBox.Show("成功关闭数据库连接", "提示信息", MessageBoxButtons.YesNoCancel);}

2.web.config配置

C#后台处理程序

string connectionString =ConfigurationManager.ConnectionStrings["myschool"].ConnectionString;

private string strCon = ConfigurationManager.AppSettings["ConnectionString"];