C # ADO. NET parameter query

1 usingSystem;2 usingSystem.Collections.Generic;3 usingSystem.ComponentModel;4 usingSystem.Data;5 usingSystem.Data.SqlClient;6 usingSystem.Drawing;7 usingSystem.Text;8 usingSystem.Windows.Forms;9 Ten namespaceAdotwo One { A      Public Partial classFlogin:form -     { -          PublicFlogin () the         { - InitializeComponent (); -         } -  +         Private voidBtnok_click (Objectsender, EventArgs e) -         { +             stringTname = TxtName.Text.Trim ();//a A             stringTpwd = TxtPwd.Text.Trim ();//b at             //determine whether the user name password is correct is actually to go to the database query there is no data, -             //This data is user name equal to user input username, -             //and -             //a password equals a single piece of data entered by the user -SqlConnection conn =NewSqlConnection ("server=.; Database=heimablog;uid=sa;pwd=suncoder"); -             stringSql=string. Format ("select COUNT (id) from Student where Name= ' {0} ' and pwd= ' {1} '", tname,tpwd); inSqlCommand cmd =NewSqlCommand (SQL, conn); -             //cmd. Connection = conn; to             //cmd.commandtext = ""; + Conn. Open (); -  the             //SqlDataReader dr = cmd. ExecuteReader (); *             //if (Dr. HasRows) $             //{Panax Notoginseng             //MessageBox.Show ("Landing Success"); -             //} the             //While (Dr. Read ()) +             //{ A             //Console.WriteLine (Dr[1]. ToString ());//+dr["Name"],DR. GetString (1)); the             //} +  -             ObjectOBG =cmd. ExecuteScalar (); $             intres =Convert.ToInt32 (OBG); $             if(Res >0) {MessageBox.Show ("Landing Success"); } -             Else{MessageBox.Show ("Login Failed"); } -         } the  -         Private voidBtnloginpara_click (Objectsender, EventArgs e)Wuyi         { theSqlConnection conn =NewSqlConnection ("server=.; Database=heimablog;uid=sa;pwd=suncoder"); -SqlCommand cmd =NewSqlCommand ("select COUNT (id) from Student where [email protected] and [email protected]", conn); Wu  -             //The first form of a notation About             //SqlParameter sp = new SqlParameter ("@ass", TxtName.Text.Trim ()); $             //SqlParameter SP2 = new SqlParameter ("@add", TxtPwd.Text.Trim ()); -  -             //cmd. Parameters.Add (SP); -             //cmd. Parameters.Add (SP2); A  +             //the second kind of writing, the special case error the             //cmd. Parameters.Add (New SqlParameter ("@ass", TxtName.Text.Trim ())); -             //cmd. Parameters.Add (New SqlParameter ("@add", TxtPwd.Text.Trim ())); $  the             //The Third kind of wording the             //sqlparameter[] Spa = new sqlparameter[]{ the             //New SqlParameter ("@ass", TxtName.Text.Trim ()), the             //New SqlParameter ("@add", TxtPwd.Text.Trim ()) -             //}; in             //cmd. Parameters.addrange (SPA); the  the             //The fourth kind of notation About             //cmd. Parameters.addwithvalue ("@ass", TxtName.Text.Trim ()); the             //cmd. Parameters.addwithvalue ("@add", TxtPwd.Text.Trim ()); the  the             //the fifth way, parameters can be output parameters +             //SqlParameter sp = new SqlParameter ("@ass", SqlDbType.NVarChar); -             //SqlParameter SP2 = new SqlParameter ("@add", SqlDbType.Char); the             //sp. Value = TxtName.Text.Trim ();Bayi             //SP2. Value = TxtPwd.Text.Trim (); the             //cmd. Parameters.Add (SP); the             //cmd. Parameters.Add (SP2); -  -             //The sixth kind of notation theSqlParameter sp =NewSqlParameter ("@ass", SqlDbType.NVarChar) {Value =TxtName.Text.Trim ()}; theSqlParameter SP2 =NewSqlParameter ("@add", SqlDbType.Char) {Value =TxtPwd.Text.Trim ()}; the cmd. Parameters.Add (SP); the cmd. Parameters.Add (SP2); -  the Conn. Open (); the  the MessageBox.Show (cmd. ExecuteScalar (). ToString ());94  the         } the     } the}

C # ADO. NET parameter query