Question

我仍然遇到组合框的问题。我有正确的查询。我在MS Access中有四个表。我需要在Visual Basic中创建一个具有组合框和数据网格的表单。从组合框中选择将在数据网格上显示有关该人员的所有相关信息。

例如，如果我选择John Doe（来自组合框），数据网格应显示：

customer_name（John Doe）order_date（01/01/01）item（Widget）price（9.99）

我的查询是：

`SELECT customers.customer_name, customers.customer_id, orders.order_date, 
orders.order_id, items.item_description, items.item_id, items.item_price
FROM (customers, orders, items) 
LEFT JOIN order_items ON orders.order_id = order_items.order_id
AND items.item_id = order_items.item_id
HERE customers.customer_name = 'John Doe'
`AND customers.customer_id = orders.order_id
ORDER BY orders.order_id, items.item_id;`

如何将John Doe添加到组合框并将此查询链接到它，在被选中时，它会在数据网格中显示结果？

谢谢。任何帮助表示赞赏。

Answer 1

首先尝试将客户加载到组合框中，创建在用户选择值时触发的事件，然后获取该客户的数据并将其绑定到datagridview

 Private Sub LoadCustomers()
        Dim cmd As New SqlCommand
        cmd.CommandText = "SELECT customers.customer_name, customers.customer_id FROM customers "
        cmd.Connection = yourConnectionObject

        Dim myCombo As ComboBox

        Dim ds As DataSet
        Dim da As SqlDataAdapter

        Try
            da.SelectCommand = cmd
            da.Fill(ds, "Customers")

            ' this will load customers to combobox
            With myCombo
                .DataSource = ds.Tables(0).DefaultView
                .DisplayMember = "customer_name"
                .ValueMember = "customer_id"
            End With

        Catch ex As Exception
        Finally
        End Try
    End Sub

    ' create one event that fires when the user changes the selected value on the combobox
    ' this is only a example, create your own method properly
    Private Sub combobox_selectedvaluechanged() Handles combobox.SelectedValueChanged()
        Dim CustomerId As Integer
        Try
            ' here you get the selected customer id
            CustomerId = ComboBox.SelectedValue

            ' Now you can retrieve data for this customer with your sql query
            ' and for better results use the customer id to run the query

            Dim ds As DataSet = GetDataForCustomer(CustomerId) ' as dataset

            ' bind the returned dataset to the datagrid
            yourdatagrid.Datasource = ds

        Catch ex As Exception

        End Try
    End Sub

Visual Basic 2010组合框到datagrid

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