private void button1_Click(object sender, EventArgs e)
    {
      using (SqlConnection con = new SqlConnection("server=.; database=text; integrated security=SSPI;"))
      {
        using (SqlCommand com = new SqlCommand())
        {
          com.CommandText = "select * from T_Users where UserName=@username";
          com.Connection = con;
          con.Open();
          com.Parameters.Add(new SqlParameter("username", txbUserName.Text));
          //com.Parameters.Add(new SqlParameter("password", textBox2.Text));
          using (SqlDataReader read = com.ExecuteReader())
          {
            if (read.Read())
            {
              int errortimes = read.GetInt32(read.GetOrdinal("ErrorTimes")); //讀取錯(cuò)誤登陸次數(shù)
              if (errortimes >= 3)    //判斷錯(cuò)誤次數(shù)是否大于等于三
              {
                MessageBox.Show("sorry 你已經(jīng)不能再登陸了！");
              }
              else
              {
                string passwored = read.GetString(read.GetOrdinal("PassWord"));
                if (passwored == txbPassWord.Text)
                {
                  MessageBox.Show("登陸成功！");
                  this.qingling();        //登陸成功把錯(cuò)誤登陸次數(shù)清零
                }
                else
                {
                  MessageBox.Show("登陸失??！");
                  this.leiji();        //登陸失敗把錯(cuò)誤登陸次數(shù)加一
                }
              }
            }
          }
        }
      }
    }

累加錯(cuò)誤登陸次數(shù)函數(shù)：

public void leiji()
    {
      using (SqlConnection con = new SqlConnection("server=.; database=text; integrated security=SSPI;"))
      {
        using (SqlCommand com = new SqlCommand())
        {
          com.Connection = con;
          com.CommandText = "update T_Users set ErrorTimes=ErrorTimes+1 where UserName=@username";
          com.Parameters.Add(new SqlParameter("username", txbUserName.Text));
          con.Open();
          com.ExecuteNonQuery();
        }
      } 
    }

清零錯(cuò)誤登陸次數(shù)函數(shù)：

 public void qingling()
    {
      using (SqlConnection con = new SqlConnection("server=.; database=text; integrated security=SSPI;"))
      {
        using (SqlCommand com = new SqlCommand())
        {
          com.Connection = con;
          com.CommandText = "update T_Users set ErrorTimes=0 where UserName=@username";
          com.Parameters.Add(new SqlParameter("username", txbUserName.Text));
          con.Open();
          com.ExecuteNonQuery();
        }
      }
    }

在button事件的代碼中小編使用了using，關(guān)于using的用法與好處在《談C# using的用法與好處》中已經(jīng)寫過。

以上就是本文的全部?jī)?nèi)容，希望對(duì)大家的學(xué)習(xí)有所幫助。

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