Question

我有点绝望，所以为什么我在这里！我对编程很新，并且已经给出了一个任务，我需要使用一系列SQL查询来生成一个简单的HTML报表。还有一个用户输入，他们从组合框中选择ClinicID并单击按钮来生成报告。

基本上，我有一个用'ClinicID'填充的comboBox，如下所示。我还确保SelectedIndex正在运行。我需要以某种方式在我在下面提供的SQL查询方法中使用它。

Public Class frmReport1
'Set lsData for Clinics table
Dim lsData As List(Of Hashtable)


'On form load
Private Sub frmReport1_Load(sender As Object, e As EventArgs) Handles MyBase.Load

    cboClinicID.DropDownStyle = ComboBoxStyle.DropDownList

    'Instantiate new ClinicController object
    Dim cController As ClinicController = New ClinicController

    'Load ClinicID
    lsData = cController.findId()

    For Each clinic In lsData
        cboClinicID.Items.Add(CStr(clinic("ClinicID")))
    Next

End Sub

'Selected Index 
Private Sub cboClinicID_SelectedIndexChanged(sender As Object, e As EventArgs) Handles cboClinicID.SelectedIndexChanged
    Dim selectedIndex As Integer = cboClinicID.SelectedIndex
    Dim selectedItem As Object = cboClinicID.SelectedItem

    'Print in debug window
    Debug.Print("Selected clinicID: " & selectedItem.ToString())
    Debug.Print("Selected clinicID index: " & selectedIndex.ToString())

    Dim htData = lsData.Item(selectedIndex)


End Sub

SQL查询方法 - **注意，我从两个不同的表中提取：

哪里'？'是，我认为我必须在'SelectedItem'工作，但我不知道如何！

所需结果：使用这三个选定字段输出的html表格。

Public Class ClinicOrderController

Public Const CONNECTION_STRING As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=PharmDB.accdb"

'Dim cController As ClinicController = New ClinicController
'Dim oController As OrderController = New OrderController

Public Function findClinicOrder() As List(Of Hashtable)

    'Instantiates a connection object
    Dim oConnection As OleDbConnection = New OleDbConnection(CONNECTION_STRING)
    'Instantiates a list of hashtables
    Dim lsData As New List(Of Hashtable)

    Try
        Debug.Print("Connection string: " & oConnection.ConnectionString)

        oConnection.Open()
        Dim oCommand As OleDbCommand = New OleDbCommand
        oCommand.Connection = oConnection

        'Stored in the CommandText property of the command object
        'SELECT SQL statement
        oCommand.CommandText = "SELECT clinics.clinic_id, orders.date_ordered, orders.total_price FROM clinics, orders WHERE clinics.clinic_id = orders.clinic_id AND clinics.clinic_id = ? ORDER BY clinics.clinic_id"

        'Compiles the prepared statement
        'oCommand.Prepare()
        'Executes the SQL statement and stores the results in data reader object
        Dim oDataReader = oCommand.ExecuteReader()

        'Process data set in Hashtable
        Dim htTempData As Hashtable
        Do While oDataReader.Read() = True
            htTempData = New Hashtable
            htTempData("ClinicID") = CStr(oDataReader("clinic_id"))
            htTempData("DateOrdered") = CStr(oDataReader("date_ordered"))
            htTempData("OrderTotalPrice") = CStr(oDataReader("total_price"))
            lsData.Add(htTempData)

        Loop

        Debug.Print("The record was found.")

    Catch ex As Exception
        Debug.Print("ERROR:" & ex.Message)
        MsgBox("An error occured!")
    Finally
        oConnection.Close()
    End Try

    'Return list of hashtables to the calling function
    Return lsData

End Function

真的，非常感谢这里的任何帮助。我已经挣扎了8个多小时（不是开玩笑 - 我允许你笑）

Answer 1

如果我理解正确，您希望在dropdown子句中使用WHERE所选项目。要实现这一点，请使用INNER JOIN ON修改您的加入，然后将过滤设置为WHERE条件。下面的希望代码会有所帮助。

    SELECT clinics.clinic_id,
      , orders.date_ordered
      , orders.total_price 
    FROM clinics INNER JOIN orders ON clinics.clinic_id = orders.clinic_id
    WHERE clinics.clinic_id = selectedItem.ToString()
    ORDER BY clinics.clinic_id

如果selectedItem.ToString（）不起作用，您可以尝试SelectedValue

Answer 2

假设clinic_id是数据库中的数字字段:(否则只用单引号括起来（＆＃39;＆＃39;））

string clinicID = cboClinicID.SelectedItem.ToString();
string sql = string.Format(@"SELECT clinics.clinic_id, orders.date_ordered, orders.total_price
                             FROM clinics, orders
                             WHERE clinics.clinic_id = orders.clinic_id
                             AND clinics.clinic_id = {0}
                             ORDER BY clinics.clinic_id", clinicID);

oCommand.CommandText = sql;

你也可以这样做：

string sql = "SELECT clinics.clinic_id, orders.date_ordered, orders.total_price " +
             "FROM clinics, orders " +
             "WHERE clinics.clinic_id = orders.clinic_id " +
             "AND clinics.clinic_id = " + clinicID + " " +
             "ORDER BY clinics.clinic_id";

Answer 3

请在vb.net中提供代码

这是我的代码，我想显示class id条件的表格中的奖金额：

如果class id为3，那么奖品将显示在名为txtprize.text的文本框中，class Id会显示在列表框中。

Private Sub listClassID_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles listClassID.SelectedIndexChanged
Dim classIdlist As String
classIdlist = New String(listClassID.SelectedItem.ToString)
Dim strSQL As String = "select [Prize Amount] from Master_Class WHERE [Class ID]  =" & classIdlist
Dim dr As SqlDataReader

Try
    con.Open()
    cmd = New SqlCommand(strSQL, con)
    dr = cmd.ExecuteReader()
    If dr.Item(0) Then
        txtPrize.Text = dr("[Prize Amount]").ToString
    End If

    dr.Close()
    cmd.Dispose()
    con.Close()

Catch ex As Exception
    MsgBox(ex.Message)
    con.Close()
End Try
End Sub

获取combobox SelectedIndex数据并在SELECT Query - VB.net中使用

3 个答案: