qtsqlbase 参数化访问数据库 SqlCommand cmd=cnn.CreateCommand()

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using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; using System.Configuration; using System.Data.SqlClient; namespace 复习登录 { public partial class login : Form { public login() { InitializeComponent(); } string str = ConfigurationManager.ConnectionStrings["sqlserver2008"].ConnectionString; DateTime dt1; private void btn_login_Click(object sender, EventArgs e) { using(SqlConnection cnn=new SqlConnection(str)) { using (SqlCommand cmd=cnn.CreateCommand()) { cmd.CommandText = "select * from T_User where username=@username"; cmd.Parameters.AddWithValue("@username", txt_username.Text); cnn.Open(); using (SqlDataReader reader = cmd.ExecuteReader()) { if (reader.Read()) { int Error = Convert.ToInt32(reader["Error"].ToString()); if (Error >= 3) { string sqltime = reader["Errortime"].ToString(); dt1 = DateTime.Parse(sqltime); DateTime dt2 = DateTime.Now; TimeSpan ts = dt2 - dt1; if (ts.TotalMinutes < 5) { MessageBox.Show("对不起，你已经输入3次连续错误密码，系统已经将账户冻结，请在五分钟后再试"); return; } else { clearerror(); } } string sqlpassword = reader["Password"].ToString(); if (sqlpassword == txt_password.Text) { clearerror(); if (txt_username.Text.ToUpper() == "ADMIN") { this.Hide(); main m = new main(); m.Show(); } else { MessageBox.Show("登录成功"); } } else { MessageBox.Show("密码错误"); adderror(); } } else { MessageBox.Show("用户名不存在"); } } } } } private void adderror() { dt1 = DateTime.Now; using (SqlConnection cnn=new SqlConnection(str)) { using (SqlCommand cmd=cnn.CreateCommand()) { cnn.Open(); cmd.CommandText = "update T_User set Error=Error+1,Errortime=@Errortime where username=@username"; cmd.Parameters.AddWithValue("@Errortime", dt1); cmd.Parameters.AddWithValue("@username", txt_username.Text); cmd.ExecuteNonQuery(); } } } private void clearerror() { using (SqlConnection cnn=new SqlConnection(str)) { using (SqlCommand cmd=cnn.CreateCommand()) { cnn.Open(); cmd.CommandText = "update T_User set Error=0 where username=@username"; cmd.Parameters.Add(new SqlParameter("username", txt_username.Text)); cmd.ExecuteNonQuery(); } } } } }

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