Question

我正在尝试使用mysql中的表中的数据填充我的组合框，这是我的代码，我看不出是什么问题。我的组合框不会返回任何数据，只是空白。

    Private Sub cbxCompanyName_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles cbxCompanyName.SelectedIndexChanged
    Dim con As New MySqlConnection
    Dim constr As String = "Server=localhost;database=ba-solutions;user id=root;password="
    Try
        con.ConnectionString = constr
        con.Open()
    Catch ex As SqlException
        MsgBox(ex.Message)
    End Try

    Dim StrSql As String = "SELECT Company Name FROM client_details"
    Dim cmd As New MySqlCommand(StrSql, objconnection)
    Dim da As MySqlDataAdapter = New MySqlDataAdapter(cmd)
    Dim dt As New DataTable("Client_details")

    da.Fill(dt)


    If dt.Rows.Count > 0 Then

        cbxCompanyName.DataSource = dt
        cbxCompanyName.DisplayMember = "Company Name" 'What is displayed

    End If

End Sub

Answer 1

试试这个

If dt.Rows.Count > 0 Then

    cbxCompanyName.DataSource = dt
    cbxCompanyName.DisplayMember = "Company Name"
    cbxCompanyName.ValueMember = "Company Name"

End If

Answer 2

试试这个..！

如果dt.Rows.Count＆gt; 0然后

    cbxCompanyName.DataSource = dt
    **cbxCompanyName.DataBind();**

End If

Answer 3

你的sql命令文本错误。如果列名或表名中有空格，则应将名称括在一个特殊字符中，该字符用于分隔列名的开头和结尾。

Dim StrSql As String = "SELECT `Company Name` FROM client_details"
Dim cmd As New MySqlCommand(StrSql, objconnection)
Dim da As MySqlDataAdapter = New MySqlDataAdapter(cmd)
Dim dt As New DataTable("Client_details")

对于MySql，这个特殊字符是反引号（按住 ALT 并在数字键盘上按 096 ）。

当然，最好避开这些空间。
如果还不晚，我建议更改该列名，删除空格

Answer 4

Private Sub cbxCompanyName_SelectedIndexChanged（sender As System.Object，e As System.EventArgs）处理cbxCompanyName.SelectedIndexChanged Dim con As New MySqlConnection Dim constr As String =“Server = localhost; database = ba-solutions; user id = root; password =” 尝试 con.ConnectionString = constr con.Open（） Catch ex As SqlException MSGBOX（ex.Message）结束尝试

Dim StrSql As String = "SELECT Company Name FROM client_details"
Dim cmd As New MySqlCommand(StrSql, objconnection)

Dim dr As OleDbDataReader = cmd.ExecuteReader

 While dr.Read
     cbxCompanyName.items.add(dr.item(0))
 End While
 dr.close()

End Sub

Answer 5

当放入组合框时，以上所有内容都是正确的，但有一点是省略的。为了立即访问该列表，必须为所选项目设置起始索引，否则您将返回＆＃39; System.Data.DataRowView＆＃39;的内容。什么时候去收集ComboBox1.Text的内容。

da.SelectCommand = cmd
ds = New DataSet
Dim dt As New DataTable
da.Fill(ds, Table)
ComboBox1.DataSource = ds.Tables(0)
ComboBox1.DisplayMember = "imgURL"
conn.Close()
da.Dispose()
conn.Dispose()
ComboBox1.SelectionStart = 0 'This is what is missing from above.
Dim current_imgURL As String = "http://10.1.1.10/photos/" & ComboBox1.Text
PictureBox1.Image = New Bitmap(New IO.MemoryStream(New WebClient().DownloadData(current_imgURL)))

此示例加载带有图像文件名的组合框，并从服务器位置拉出它们。我想在从MySql填充后立即从组合框中预加载第一个图像并遇到这个问题，因为只有当用户点击组合框时才触发选择索引，而不是在加载数据时触发。

Answer 6

尝试此代码我希望它能够正常工作

Dim con As New MySqlConnection("connection string")
Dim da As New MySqlDataAdapter("SELECT * FROM tableName", con)
Dim dt As New DataTable

da.Fill(dt)
ComboBox1.DisplayMember = "fieldName to show in ComboBox"enter code here
ComboBox1.DataSource = dt
TextBox1.DataBindings.Add("Text", dt, "fieldName to show in textbox")

使用来自MySQL的数据填充组合框

6 个答案: