它只显示列但数据没有出现......？请帮帮我 [英] Its only showing the columns but data is not appearing...? Please help me on this

问题描述

 public partial class Window_search：Window 
 {
 public Window_search（）
 {
 InitializeComponent（）; 
} 
 
 private void Search_button_Click_1（对象发送者，RoutedEventArgs e）
 {
 var id = Device_id_TextBox.ToString（）; 
 MySqlConnection con = new MySqlConnection（database）; 
 con.Open（）; 
 DataTable devicetable = new DataTable（）; 
 MySqlDataAdapter adapter = new MySqlDataAdapter（SELECT`Device_ID`，`Device_Name`，`Devic_Category`，`Status`，`Description`，`Customer_ID`，`Customer_Name` FROM`devicedetails` WHERE`Device_ID` ='id ，CON）; 
 
尝试
 {
 
 adapter.Fill（devicetable）; 
 table_grid_view.DataContext = devicetable; 
 con.Close（）; 
} 
 catch（Exception Ex）
 {
 MessageBox.Show（Ex.Message）; 
} 
 
 
} 
 
 
} 

< pre lang =   c＃>< pre lang =    c＃ >  

我尝试过：

公共部分类Window_search：Window 
 {
 public Window_search（）
 {
 InitializeComponent（）; 
} 
 
 private void Search_button_Click_1（对象发送者，RoutedEventArgs e）
 {
 var id = Device_id_TextBox.ToString（）; 
 MySqlConnection con = new MySqlConnection（database）; 
 con.Open（）; 
 DataTable devicetable = new DataTable（）; 
 MySqlDataAdapter adapter = new MySqlDataAdapter（SELECT`Device_ID`，`Device_Name`，`Devic_Category`，`Status`，`Description`，`Customer_ID`，`Customer_Name` FROM`devicedetails` WHERE`Device_ID` ='id ，CON）; 
 
尝试
 {
 
 adapter.Fill（devicetable）; 
 table_grid_view.DataContext = devicetable; 
 con.Close（）; 
} 
 catch（Exception Ex）
 {
 MessageBox.Show（Ex.Message）; 
} 
 
 
} 
 
 
} 

解决方案

查看你的代码：

 MySqlDataAdapter adapter = new MySqlDataAdapter（SELECT`Device_ID`，`Device_Name`，`Devic_Category`，`Status`，`Description `，`Customer_ID`，`Customer_Name` FROM`devicedetails` WHERE`Device_ID` ='id'，con）; 
 

您只获取与显式和固定条件匹配的记录： Device_ID 列包含字符串id。如果没有列匹配 - 我非常怀疑是否有 - 你将没有返回任何行。



可能你想传递一个ID值作为参数查询并返回匹配的行，而不是固定的字符串：参数化查询MySQL | @Henning [ ^ ]

public partial class Window_search : Window
    {
        public Window_search()
        {
            InitializeComponent();
        }

        private void Search_button_Click_1(object sender, RoutedEventArgs e)
        {
            var id = Device_id_TextBox.ToString(); 
            MySqlConnection con = new MySqlConnection("database");
            con.Open();
            DataTable devicetable = new DataTable();
            MySqlDataAdapter adapter = new MySqlDataAdapter("SELECT `Device_ID`, `Device_Name`, `Devic_Category`, `Status`, `Description`, `Customer_ID`, `Customer_Name` FROM `devicedetails` WHERE `Device_ID` = 'id'",con);

            try
            {
                
                adapter.Fill(devicetable);
                table_grid_view.DataContext = devicetable;
                con.Close();
            }
            catch (Exception Ex)
            {
                MessageBox.Show(Ex.Message);
            }
      

        }

        
    }

<pre lang="c#"><pre lang="c#">

What I have tried:

public partial class Window_search : Window
    {
        public Window_search()
        {
            InitializeComponent();
        }

        private void Search_button_Click_1(object sender, RoutedEventArgs e)
        {
            var id = Device_id_TextBox.ToString(); 
            MySqlConnection con = new MySqlConnection("database");
            con.Open();
            DataTable devicetable = new DataTable();
            MySqlDataAdapter adapter = new MySqlDataAdapter("SELECT `Device_ID`, `Device_Name`, `Devic_Category`, `Status`, `Description`, `Customer_ID`, `Customer_Name` FROM `devicedetails` WHERE `Device_ID` = 'id'",con);

            try
            {
                
                adapter.Fill(devicetable);
                table_grid_view.DataContext = devicetable;
                con.Close();
            }
            catch (Exception Ex)
            {
                MessageBox.Show(Ex.Message);
            }
      

        }

        
    }

解决方案

Look at your code:

MySqlDataAdapter adapter = new MySqlDataAdapter("SELECT `Device_ID`, `Device_Name`, `Devic_Category`, `Status`, `Description`, `Customer_ID`, `Customer_Name` FROM `devicedetails` WHERE `Device_ID` = 'id'",con);

You are fetching only records which match an explicit and fixed condition: that the Device_ID columns contains the string "id". If no columns match that - and I very much doubt if any do - you will get no rows returned.

Probably, you wanted to pass an ID value as a parameter to the query and return matching rows, rather than a fixed string: Parameterized queries in MySQL | @Henning[^]

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