如何在C＃Windapp中使用Displayvalue和Displaymember在Combobox中检索数据

本文介绍了如何在C＃Windapp中使用Displayvalue和Displaymember在Combobox中检索数据的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述 void FillComboBoxRepair() { try { con.Open(); s = "select * from Repair_Type"; sd = new SqlCommand(s,con); sda = sd.ExecuteReader(); while (sda.Read()) { string Repair_type = sda.GetString(1); CB_Repair_type.Items.Add(Repair_type); } con.Close(); } catch(Exception ex) { MessageBox.Show(ex.Message); } 推荐答案 void FillComboBoxRepair() { try { con.Open(); s = "SELECT ID, Description FROM Repair_Type"; using (sd = new SqlCommand(s, con)) { DataTable dt = new DataTable(); using (SqlDataAdapter da = new SqlDataAdapter(sd)) { da.Fill(dt); CB_Repair_type.DataSource = dt; CB_Repair_type.DisplayMember = "Description"; CB_Repair_type.ValueMember = "ID"; } } con.Close(); } catch (Exception ex) { MessageBox.Show(ex.Message); } } 现在ComboBox显示Description并返回描述字符串的ID值。Now the ComboBox displays the Description and returns the ID value for the description string. // in some Classpublic struct ComboStruct{ public string PublicString1 { set; get; } public string PublicString2 { set; get; } public ComboStruct(string s1, string s2) : this() { PublicString1 = s1; PublicString2 = s2; }}public List<ComboStruct> ComboData = new List<ComboStruct>();// in a Method in the Class like a Form Load EventHandler:private void Form1_Load(object sender, EventArgs e){ // build the List for (int i = 0; i < 10; i++) { string s = i.ToString(); ComboData.Add(new ComboStruct(string.Format("s1:{0}", s), string.Format("s2:{0}", s))); } // set the DataSource to the List comboBox1.DataSource = ComboData; // set the Display/Value Members comboBox1.DisplayMember = "PublicString1"; comboBox1.ValueMember = "PublicString2";}现在您可以为ComboBox定义'SelectedIndexChanged EventHandler并获取ValueMember：Now you can define a 'SelectedIndexChanged EventHandler for the ComboBox and get the ValueMember:private void comboBox1_SelectedIndexChanged(object sender, EventArgs e){ string vMember = comboBox1.SelectedValue.ToString(); Console.WriteLine(vMember);}值得注意的是，当您获得'SelectedValue时，您将获得对您设置为'ValueMember的属性的值的引用。但是，ValueMember总是将价值装箱作为对象;要将它用作String，我们需要将其转换为String。It is important to note that when you get the 'SelectedValue, you are getting a reference to the Value of the Property you set to be the 'ValueMember. But, the ValueMember is always going to be that 'Value "boxed" as an Object; to use it as a String, we need to cast it to a String. public partial class Form1 : Form{ public Form1() { InitializeComponent(); DataTable dt = new DataTable(); dt.Columns.Add("ID", typeof(int)); dt.Columns.Add("Name", typeof(string)); DataRow row1 = dt.NewRow(); row1["ID"] = 1; row1["Name"] = "First"; dt.Rows.Add(row1); DataRow row2 = dt.NewRow(); row2["ID"] = 2; row2["Name"] = "Second"; dt.Rows.Add(row2); ExampleComboBox.ValueMember = "ID"; ExampleComboBox.DisplayMember = "Name"; ExampleComboBox.DataSource = dt; ExampleComboBox.SelectedValue = 1; // set the initial selection ExampleComboBox.SelectedIndexChanged += ExampleComboBoxSelectedIndexChanged; } private void ExampleComboBoxSelectedIndexChanged(object sender, EventArgs e) { int selectedID = (int)ExampleComboBox.SelectedValue; // get the current selection }} 要将它与从数据库中读取的代码集成，您需要将记录读入一个对象，而不是ComboBox可用作DataSource的对象。我建议你使用DataTable。 另外一点，你的数据库访问代码有很多不太好的东西： - 不要将连接，命令和读取器对象声明为类成员。在方法中声明它们 - 在方法中。 - 使用使用 -statements和所有一次性对象。这将使得关闭连接成为不必要的，并且在发生异常时将阻止它保持打开状态。目前，它将保持打开状态，因为它不会到达con.Close（）行。同样，对于除连接之外的其他一次性对象，使用使用 -statement将确保在完成后释放已分配的资源。 - 使用抽象Db ***** - 基类或IDb ***** - 接口（如DbConnection，DbCommand，..）而不是像SqlConnection，SqlCommand等数据库系统特定的接口。看看 DbProviderFactory [ ^ ]。To integrate it with your code that reads from the database you need to read the records into an object than can be used as a DataSource by the ComboBox. I would recommend you to use a DataTable for that.On a different note, there's a lot of not-so-good stuff about your database-access code:- Don't declare the connection, command and reader objects as class members. Declare them where you need them - in the method.- Use using-statements with all disposable objects. This will make it unneccessary to close the connection and will prevent it from staying open in case an exception occurs. Currently, it would stay open because it wouldn't reach the con.Close() line. Likewise for other disposable objects than the connection, using them with a using-statement will ensure you are freeing the allocated resources when you're done.- Use the abstract Db*****-baseclasses or IDb*****-interfaces (like DbConnection, DbCommand,..) rather than the database-system specific ones like SqlConnection, SqlCommand etc. Take a look at DbProviderFactory[^]. 这篇关于如何在C＃Windapp中使用Displayvalue和Displaymember在Combobox中检索数据的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！