Ado.net的初步連結

標籤：c   style   class   blog   code   java   

            string connStr = "Data Source=.;Initial Catalog=MySchoolMoreData;Integrated Security=True";            try            {                using (SqlConnection conn = new SqlConnection(connStr))                {                    //開啟串連                    conn.Open();                    MessageBox.Show("ok");                    //conn.Close();                    conn.Dispose(); //沒用釋放只是清空了連接字串                    conn.ConnectionString = connStr;                    conn.Open();                    MessageBox.Show("ok2");                 }            }            catch(Exception ex)            {                MessageBox.Show(ex.Message);            }        }        private void btnPool_Click(object sender, EventArgs e)        {                        string connStr = "Data Source=.;Initial Catalog=MySchoolMoreData;Integrated Security=True;pooling=false"; //0,2   2.9    6.0  9            string sql = "select * from grade";            Stopwatch sw = new Stopwatch();//建立一個秒錶            sw.Start();            for (int i = 0; i < 1000; i++)            {                using (SqlConnection conn = new SqlConnection(connStr))                {                    //SqlConnection conn = new SqlConnection(connStr);                    SqlCommand comm = new SqlCommand(sql, conn);                    comm.ExecuteScalar();                    conn.Close();                 }                //SqlConnection conn = new SqlConnection(connStr);            }            sw.Stop();            MessageBox.Show(sw.Elapsed.ToString());        }        private void btnState_Click(object sender, EventArgs e)        {            string connStr = "Data Source=.;Initial Catalog=MySchoolMoreData;Integrated Security=True;pooling=false";            SqlConnection conn = new SqlConnection(connStr);            conn.StateChange += Change;            conn.Open();            conn.Close();        }        void Change(object sender, StateChangeEventArgs e)        {            MessageBox.Show(e.OriginalState+"   "+e.CurrentState);        }        private void btnGetId_Click(object sender, EventArgs e)        {            string connStr = "Data Source=.;Initial Catalog=MySchoolMoreData;Integrated Security=True;pooling=false";            using(SqlConnection conn=new SqlConnection(connStr))            {                conn.Open();                //string sql = "insert into grade values(‘" + txtName.Text.Trim() + "‘);select @@identity";                string sql = " insert into grade output inserted.classid values(‘" + txtName.Text.Trim() + "‘)";                //方法的意義不在於執行那一些命令，而在於能夠接收到某種操作類型的傳回值                SqlCommand command = new SqlCommand(sql, conn);                //調用什麼方法，由你那一種類型的傳回值決定                int obj =Convert.ToInt32(command.ExecuteScalar());                MessageBox.Show("識別欄位值是："+obj);            }        }    }