C#_ Connection Database Implementation Login Registration interface

//Write Login interface logicusingSystem;usingSystem.Collections.Generic;usingSystem.ComponentModel;usingSystem.Data;usingSystem.Drawing;usingSystem.Linq;usingSystem.Text;usingSystem.Threading.Tasks;usingSystem.Windows.Forms;usingSystem.Data.SqlClient;namespacelogindatabase{ Public Partial classLogin:form {Private intErrortime =3;  PublicLogin () {InitializeComponent (); }        Private voidLoginbtn_click (Objectsender, EventArgs e) {Errortime= Errortime-1; stringUsername = TxtName.Text.Trim ();//Remove Account            stringPW = TxtPwd.Text.Trim ();//Remove Password            stringConstr ="server=.;D ATABASE=SU; Integrated security=true";//Setting the connection stringSqlConnection Mycon =NewSqlConnection (CONSTR);//instantiating a Connection objectMycon.            Open (); SqlCommand mycom= Mycon. CreateCommand ();//To create an SQL command execution object            stringS1 ="Select Account,password from register where account= '"+ Username +"' and password= '"+ PW +"'";//Writing SQL CommandsMycom.commandtext = S1;//Execute SQL commandSqlDataAdapter Myda =NewSqlDataAdapter ();//instantiating a data adapterMyda.selectcommand = mycom;//to have the adapter execute the SELECT commandDataSet MyDS =NewDataSet ();//instantiating the result data set            intn = Myda.fill (MyDS,"Register");//put the result in the data adapter, return the number of tuples            if(n! =0) {                if(Checkcode.text = =textcheck.text) {MessageBox.Show ("Welcome to use! ");//Login Successful                     This.                Close (); } Else{MessageBox.Show ("Verification Code filling error"); Textcheck.text=""; }            } Else                if(Errortime <3) {MessageBox.Show ("The user name or password is incorrect. Please re-enter! also have"+ errortime.tostring () +"Second Chance"); txtName.Text="";//Clear AccountTxtpwd.text ="";//clear Password?Txtname.focus ();//the cursor is set on the account}Else{MessageBox.Show ("have you entered a user name or password that has reached three times? will exit the program");  This.                Close (); }        }        Private voidCancelbtn_click (Objectsender, EventArgs e)        {application.exit (); }        Private voidButton1_Click (Objectsender, EventArgs e) {Register Register=NewRegister (); Register.        ShowDialog (); }        Private voidCheckcode_click (Objectsender, EventArgs e) {Random random=NewRandom (); intMINV =12345, MAXV =98765; Checkcode.text=Random. Next (MINV, MAXV).        ToString (); }    }}5. Writing Registration Interface LogicusingSystem;usingSystem.Collections.Generic;usingSystem.ComponentModel;usingSystem.Data;usingSystem.Data.SqlClient;usingSystem.Drawing;usingSystem.Linq;usingSystem.Text;usingSystem.Threading;usingSystem.Threading.Tasks;usingSystem.Windows.Forms;namespacelogindatabase{ Public Partial classRegister:form { PublicRegister () {InitializeComponent (); }        Private voidBtnregister_click (Objectsender, EventArgs e) {            //Check if it already exists            stringUserID = UserId.Text.Trim ();//Remove Account                        /** * Connect to database*/             stringConstr ="server=.;D ATABASE=SU; Integrated security=true";//Setting the connection stringSqlConnection Mycon =NewSqlConnection (CONSTR);//instantiating a Connection objectMycon.            Open (); //querying whether a newly registered user existsSqlCommand checkcmd = mycon. CreateCommand ();//To create an SQL command execution object            strings ="Select account from register where account= '"+ UserID +"'"; Checkcmd.commandtext=s; SqlDataAdapter check=NewSqlDataAdapter ();//instantiating a data adapterCheck. SelectCommand = Checkcmd;//to have the adapter execute the SELECT commandDataSet Checkdata =NewDataSet ();//instantiating the result data set            intn = check. Fill (Checkdata,"Register");//put the result in the data adapter, return the number of tuples            if(n! =0) {MessageBox.Show ("User name exists"); Userid.text=""; Userpw.text =""; Nickname.text=""; }                 //Confirm Password            if(Ensurepw.text! =userpw.text) {Ensurepw.text=""; }            //Verification Code            if(Textcheck.text! =checkcode.text) {Textcheck.text=""; }            //inserting data into SQL logic            stringS1 ="INSERT INTO Register (account,password,nickname) VALUES ('"+ Userid.text +"', '"+ Userpw.text +"', '"+ Nickname.text +"')";//Writing SQL CommandsSqlCommand mycom =NewSqlCommand (S1, mycon);//Initialize CommandMycom. ExecuteNonQuery ();//EXECUTE StatementMycon. Close ();//Close Connectionmycom =NULL; Mycon.                     Dispose (); //Releasing Objects            if(Userid.text = =""|| Userpw.textlength <=6|| Nickname.text = =""|| Ensurepw.text = =""|| Textcheck.text = ="") {MessageBox.Show ("please fill in the complete information"); } Else{MessageBox.Show ("Registration Successful");  This.            Close (); }        }        Private voidCheckcode_click (Objectsender, EventArgs e) {Random random=NewRandom (); intMINV =12345, MAXV =98765; Checkcode.text=Random. Next (MINV, MAXV).        ToString (); }    }

C#_ Connection Database Implementation Login Registration interface