我们需要通过从其他组合框中选择值来将值添加到组合框中

Question

我们需要通过从另一个组合框中选择值来将值添加到组合框。 它不会按照它应该选择的值。只有第一部分执行。 这是代码： 它不适合我们。

private void section_SelectedIndexChanged(object sender, EventArgs e) 
    { 
     string selected = (string)section.SelectedItem; 

     if(selected == "Giftarticles") 
     { 
      SqlConnection conn1 = new SqlConnection(connString); 
      conn1.Open(); 
      string itemc = "(select distinct Itemcode from Items where Section1 like 'G%')except(select distinct Itemcode from Items where Section1 like 'H%')"; 
      SqlCommand cmditem = new SqlCommand(itemc, conn1); 
      SqlDataReader dr2 = cmditem.ExecuteReader(); 

      while (dr2.Read()) 
      { 
       itemcode.Items.Add(dr2["Itemcode"].ToString()); 
      } 
      dr2.Close(); 
      conn1.Close(); 
     } 
     else 
     { 
      SqlConnection conn2 = new SqlConnection(connString); 
      conn2.Open(); 
      string itemc1 = "(select distinct Itemcode from Items where Section1 like 'H%')except(select distinct Itemcode from Items where Section1 like 'G%')"; 
      SqlCommand cmditem = new SqlCommand(itemc1, conn2); 
      SqlDataReader dr2 = cmditem.ExecuteReader(); 

      while (dr2.Read()) 
      { 
       itemcode.Items.Add(dr2["Itemcode"].ToString()); 
      } 
      dr2.Close(); 
      conn2.Close(); 
} 
    } 

Answer 1

我看到的是，如果是

和

之间

 string itemc = "(select distinct Itemcode from Items where Section1 like 'G%')except(select distinct Itemcode from Items where Section1 like 'H%')"; 

 string itemc1 = "(select distinct Itemcode from Items where Section1 like 'H%')except(select distinct Itemcode from Items where Section1 like 'G%')"; 

实际需要。

剔除这两个，其余部分显示相同。所以只有查询不能返回结果给你。独立运行这些查询，看看你是否得到结果。

Answer 2

虽然我讨厌在代码中直接利用连接，读卡器等，并会建议去的类型化的DataSet的方式，这里是应为你工作：

private void section_SelectedIndexChanged(object sender, EventArgs e) 
{ 
    string selected = (string)section.SelectedItem; 
    using(SqlConnection conn1 = new SqlConnection(connString)) 
    { 
     conn1.Open(); 
     string itemc = "select distinct Itemcode from Items where Section1 like 'G%'"; 

     if(selected != "Giftarticles") itemc += " AND Section1 NOT LIKE 'H%'" 

     SqlCommand cmditem = new SqlCommand(itemc, conn1); 
     SqlDataReader dr2 = cmditem.ExecuteReader(); 

     while (dr2.Read()) 
      itemcode.Items.Add(dr2["Itemcode"].ToString()); 

     dr2.Close(); 
     conn1.Close(); 
    } 
} 

这种替换整个上面的代码。