检索单个数据 [英] Retrieve a single data

问题描述

我开发了一个Windows窗体应用程序。有许多形式可用于数据操作。在Sales_Details的形式中，我在数据库中输入医生的信息，例如医生姓名，地址，移动等。在另一个表格中，我使用了一个comboBox控件作为医生姓名，我从Sales_Details中检索医生名称到这个组合框，其中医生姓名第一次进入。我为此编写了这段代码

 DataTable dt2 =  new  DataTable（）; 
 SqlConnection cn1 =  new  SqlConnection（Class1.cs）; 
 SqlDataAdapter da2 =  new  SqlDataAdapter（  select来自Sales_Details的Doctor_Name，cn1）; 
 da2.Fill（dt2）; 
 comboBox2.DataSource =  new  BindingSource（dt2， null ）; 
 comboBox2.DisplayMember =   Doctor_Name; 
 comboBox2.Text =  选择一个......; 
 cn1.Close（）; 

当我运行此代码时它运行正常但它检索并在comboBox中显示一个特定的医生名称5次如果我使用第一个表格输入该特定医生姓名5次; Sales_Details。我想只显示一次特定的医生姓名，无论我是否输入5或6次。请有人帮忙。

我用C＃和SQL Server 2005来开发这个应用程序。

解决方案

 < span class =code-keyword>从 Sales_Details  
 
但不是一个完美的解决方案，因为两个医生可以有相同的名字。

你应该为每个医生都有一个代码。我建议你在DropDown中显示代码和医生姓名。试试这个：

 DataTable dt2 =  new  DataTable（）; 
 SqlConnection cn1 =  new  SqlConnection（Class1.cs）; 
 SqlDataAdapter da2 =  new  SqlDataAdapter（  SELECT （Doctor_Name +' - '+ Doctor_Code）AS Doctor_Name，Doctor_Code FROM Sales_Details，cn1）; 
 da2.Fill（dt2）; 
 comboBox2.DataSource =  new  BindingSource（dt2， null ）; 
 comboBox2.DisplayMember =   Doctor_Name; 
 comboBox2.Text =  选择一个......; 
 cn1.Close（）; 

现在，如果两位医生的姓名相同，那么用户可以轻松识别他们的代码。



--Amit

_Amy是对的我的解决方案是修改后的形式

 DataTable dt2 =  new  DataTable（）; 
 SqlConnection cn1 =  new  SqlConnection（Class1.cs）; 
 SqlDataAdapter da2 =  new  SqlDataAdapter（  SELECT Doctor_Code，（Doctor_Name +' - '+ Doctor_Code）AS Doctor_Name，Doctor_Code FROM Sales_Details，cn1）; 
 da2.Fill（dt2）; 
 comboBox2.DataSource =  new  BindingSource（dt2， null ）; 
 comboBox2.DisplayMember =   Doctor_Name; 
 comboBox2.ValueMember =   Doctor_Code; 
 comboBox2.Text =  选择一个......; 
 cn1.Close（）; 

现在你可以用comboBox.SelectedValue属性获得实际的医生代码。

I developed a Windows Form Application. There are many forms available for data manipulation. In a form namely Sales_Details I enter information of a doctor in database such as Doctor Name, Address, Mobile etc. In one another form I used a comboBox control for Doctor Name, I retrieve the Doctor Name to this comboBox from Sales_Details where the Doctor Name entered first time. I wrote this code for that

DataTable dt2 = new DataTable();
SqlConnection cn1 = new SqlConnection(Class1.cs);
SqlDataAdapter da2 = new SqlDataAdapter("select Doctor_Name from Sales_Details", cn1);
da2.Fill(dt2);
comboBox2.DataSource = new BindingSource(dt2, null);
comboBox2.DisplayMember = "Doctor_Name";
comboBox2.Text = "Select One...";
cn1.Close();

while I run this code it''s running properly but it retrieves and shows in the comboBox a particular Doctor Name 5 times if I entered that particular Doctor Name 5 times by using the first form viz; Sales_Details. I want to show that particular Doctor Name only one time whether I entered it 5 or 6 times no matter. Please someone help.
I used C# and SQL Server 2005 to develop this application.

解决方案

select DISTINCT Doctor_Name from Sales_Details

But not a perfect solutions since two doctors can have the same name.

You should have a code for each doctors. I would suggest you to display code along with the doctor names in DropDown. Try this:

DataTable dt2 = new DataTable();
SqlConnection cn1 = new SqlConnection(Class1.cs);
SqlDataAdapter da2 = new SqlDataAdapter("SELECT (Doctor_Name +' - '+ Doctor_Code) AS Doctor_Name, Doctor_Code  FROM Sales_Details", cn1);
da2.Fill(dt2);
comboBox2.DataSource = new BindingSource(dt2, null);
comboBox2.DisplayMember = "Doctor_Name";
comboBox2.Text = "Select One...";
cn1.Close();

Now, if the two doctors are having same name also then user can easily identify with their codes.

--Amit

_Amy is right my solution is lite modified form

DataTable dt2 = new DataTable();
SqlConnection cn1 = new SqlConnection(Class1.cs);
SqlDataAdapter da2 = new SqlDataAdapter("SELECT Doctor_Code, (Doctor_Name +' - '+ Doctor_Code) AS Doctor_Name, Doctor_Code  FROM Sales_Details", cn1);
da2.Fill(dt2);
comboBox2.DataSource = new BindingSource(dt2, null);
comboBox2.DisplayMember = "Doctor_Name";
comboBox2.ValueMember = "Doctor_Code";
comboBox2.Text = "Select One...";
cn1.Close();

now you can get the actual doctor code with comboBox.SelectedValue property.

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