如何编写代码来显示重复的条目？ [英] How to write a code to show a duplicate entry?

问题描述

亲爱的朋友们，



我的程序差不多完成但是我面临的问题是如何写一个重复的代码？



一旦用户在电子邮件重复条目中输入密钥，就会显示错误消息。



以下是我在C＃中的代码：

Dear friends,

My program are almost done but what I'm facing an issues is how to write a duplicate code?

It is to show an error message once user had key in the Email duplicate entry.

below are my code in C#:

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.SqlClient;


namespace WebPortal
{
    public partial class DataEntry : System.Web.UI.Page
    {
        string strConnString = ConfigurationManager.ConnectionStrings["ConnectionString2"].ConnectionString;
        string str;
        SqlCommand com;

        protected void Page_Load(object sender, EventArgs e)
        {
            SqlConnection con = new SqlConnection(strConnString);

            con.Open();
            str = ("select * from staff where Username = ('" + Session["Username"] + "')");
            com = new SqlCommand(str, con);
            object obj = Session["Username"];

            SqlDataReader reader = com.ExecuteReader();
            reader.Read();
            Label1.Text = reader["Username"].ToString();
        }

        protected void Button7_Click(object sender, EventArgs e)
        {
            string connectionString = "Data Source=.\\SQLEXPRESS;"
            + "AttachDbFilename=\"C:\\Users\\KLSIT\\Documents\\Visual Studio 2008\\Projects\\WebPortal\\WebPortal\\App_Data\\emaildata.mdf\";"
            + "Integrated Security=True;"
            + "Connect Timeout=30;"
            + "User Instance=True";

            System.Data.SqlClient.SqlConnection conn = new System.Data.SqlClient.SqlConnection(connectionString);

            System.Data.SqlClient.SqlCommand cmd = conn.CreateCommand();

             
            {

                String FullName;
                String FirstName;
                String LastName;


                cmd.Parameters.Add("Type", SqlDbType.NVarChar);
                cmd.Parameters["Type"].Value = this.DropDownList2.Text;

                cmd.Parameters.Add("Title", SqlDbType.NVarChar);
                cmd.Parameters["Title"].Value = this.DropDownList1.Text;

                cmd.Parameters.Add("FirstName", SqlDbType.NVarChar);
                cmd.Parameters["FirstName"].Value = this.TextBox1.Text;

                cmd.Parameters.Add("LastName", SqlDbType.NVarChar);
                cmd.Parameters["LastName"].Value = this.TextBox2.Text;

                cmd.Parameters.Add("Fullname", SqlDbType.NVarChar);
                cmd.Parameters["Fullname"].Value = this.TextBox1.Text + " " + this.TextBox2.Text;

                cmd.Parameters.AddWithValue("Email", SqlDbType.NVarChar);
                cmd.Parameters["Email"].Value = this.TextBox3.Text.Trim();

                cmd.Parameters.Add("Job_Title", SqlDbType.NVarChar);
                cmd.Parameters["Job_Title"].Value = this.TextBox4.Text;

                cmd.Parameters.Add("Company", SqlDbType.NVarChar);
                cmd.Parameters["Company"].Value = this.TextBox5.Text;

                cmd.Parameters.Add("Mobile_Phone", SqlDbType.NVarChar);
                cmd.Parameters["Mobile_Phone"].Value = this.TextBox6.Text;

                cmd.Parameters.Add("Office_Phone", SqlDbType.NVarChar);
                cmd.Parameters["Office_Phone"].Value = this.TextBox7.Text;

                cmd.Parameters.Add("Staff", SqlDbType.NVarChar);
                cmd.Parameters["Staff"].Value = this.Label1.Text;


                FirstName = TextBox1.Text;
                LastName = TextBox2.Text;
                FullName = TextBox1.Text + " " + TextBox2.Text;

                cmd.CommandText = "INSERT INTO [Customer] ([Type], [Title], [Firstname], [Lastname], [Fullname], [Company], [Email], [Mobile_Phone], [Office_Phone], [Job_Title], [Staff]) VALUES (@Type, @Title, @Firstname, @Lastname, @Fullname, @Company, @Email, @Mobile_Phone, @Office_Phone, @Job_Title, @Staff)";


               try
                   {
                       conn.Open();
                    
                    cmd.ExecuteNonQuery();

                       ScriptManager.RegisterStartupScript(this, this.GetType(), "popup", "alert('Record Saved Successfully.');window.location='DataEntry.aspx';", true);
                   }
                   catch (Exception ex)
                   {
                       Response.Write("Oops!! Following error occured: " + ex.Message.ToString());
                   }
                   finally
                   {
                       conn.Close();
                       cmd.Dispose();
                   }
                 

            }
        }

请指教，谢谢你非常

Please advice, thank you very much

推荐答案

尝试：



来自员工的SELECT Count（Email），其中Email =参数组通过电子邮件



它将为您提供具有指定电子邮件地址的用户总数。如果该数字为0，则该用户都没有该电子邮件地址。如果它不是0，那么你有一个副本。

Try:

SELECT Count(Email) from staff where Email = parameter group by Email

It will give you the total number of users with the specified e-mail adress. If the number is 0, then none of the user's have that e-mail adress. If it's not 0, then you have a duplicate.

你好b $ b

如果你有重复的emailid你不想插入细节然后你需要在插入命令之前进行此检查



string email = TextBox3.Text.Trim（）;

string select = select tablename其中Email = @ email limit 1;

command.parameters.addwithvalue（@ email，email）;

datatable dt = new datatable（）;

sqldataadapter da = new sqldatadapter（）;

da.fill（dt）;

if（dt.rows.count> 0）

{

ScriptManager.RegisterStartupScript（this，this.GetType（），popup，alert（'Emailid exists'），true）;

return;



}



这里id表示你的主键

Hi
if u have duplicated emailid and u dont want to insert the details then u need to do this check before insert command

string email=TextBox3.Text.Trim();
string select=select id from tablename where Email=@email limit 1;
command.parameters.addwithvalue("@email",email);
datatable dt=new datatable();
sqldataadapter da= new sqldatadapter();
da.fill(dt);
if(dt.rows.count>0)
{
ScriptManager.RegisterStartupScript(this, this.GetType(), "popup", "alert('Emailid exists'),true);
return;

}

here id means your primary key

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