.net中怎么判断用户名是否重复

Question

急！请高手帮忙！

Answer 1

取得你输入的用户名
然后DataTable dt=new  DataTable ();
select * from User where UserName='用户名'
得到的数据给dT 判断dt.rows.count>1就是重复咯

Answer 2

protected void Button1_Click(object sender, EventArgs e)
{
 //查找是否有重复用户名
 List<Model.Yonghu> models = BLLServices.Yonghu.GetList(TextBox1.Text.Trim());
 if(models != null && models.Count > 0){
  lbl_UID_tips.Text = "注册用户名重复";
  return;
 }
 //添加用户名或密码
 Model.Yonghu model = new Model.Yonghu();
 model.Uid = TextBox1.Text.Trim();
 model.Pass = TextBox2.Text.Trim();
 BLLServices.Yonghu.Insert(model);
 //用户登录
 if(BLLServices.Yonghu.UserLogin(TextBox1.Text.Trim(),TextBox2.Text.Trim())){
  lbl_LOGIN_tips.Text = "登录失败，请核对用户名或密码";
  return;
 }
 Response.Redirect("~/",True);  //登录成功，返回主页
} 

Answer 3

把当前输入的用户名在用户表里查询 用count(*)，返回结果为大于或等于1,就重复，否则未重复

Answer 4

/// <summary>
        /// 执行一条计算查询结果语句，返回查询结果（object）。
        /// </summary>
        /// <param name="SQLString">计算查询结果语句</param>
        /// <returns>查询结果（object）</returns>
        public static object GetSingle(string SQLString)
        {
            using (SqlCommand cmd = new SqlCommand(SQLString, GetConn()))
            {
                try
                {
                    object obj = cmd.ExecuteScalar();
                    if ((Object.Equals(obj, null)) || (Object.Equals(obj, System.DBNull.Value)))
                    {
                        return null;
                    }
                    else
                    {
                        return obj;
                    }
                }
                catch (System.Data.SqlClient.SqlException e)
                {
                    throw e;
                }
            }        }        /// <summary>
        /// 带参数返回一行一列ExecuteScalar
        /// </summary>
        /// <param name="cmdtext">存储过程或者SQL语句</param>
        /// <param name="para">参数数组</param>
        /// <param name="ct">命令类型</param>
        /// <returns>返回一行一列value</returns>
        public static int ExecuteScalar(string cmdtext, SqlParameter[] para, CommandType ct)
        {
            int value;
            try
            {
                cmd = new SqlCommand(cmdtext, GetConn());
                cmd.CommandType = ct;
                cmd.Parameters.AddRange(para);
                value = Convert.ToInt32(cmd.ExecuteScalar());
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                if (cn.State == ConnectionState.Open)
                {
                    cn.Close();
                }
            }
            return value;
        }返回的值 来判断。

Answer 5

DataTable dt2 = ci.GetDataList(6).Tables[0];  if (itemCD == ComLibrary.ToString(dt2.Rows[0]["ITEMCD"]))
                                    {//商品重复
                                        lblMsg.Text = cm.GetMessage("E00029");
                                        lblMsg.ForeColor = Color.Red;
                                        dgvITList.CurrentCell = dgvc;
                                        dgvITList.CurrentCell.ReadOnly = false;
                                        return true;
                                    }