採取組合框SelectedIndex數據和使用SELECT查詢 - VB.net

Question

我有點絕望，因此我爲什麼在這裏！我對編程相當陌生，並且已經給了一個任務，我需要使用一系列SQL查詢來生成一個簡單的HTML報表。還有一個用戶輸入，他們從組合框中選擇ClinicID並單擊一個按鈕來生成報告。

基本上，我有一個組合框，我已經填充了'ClinicID'，如下所示。我也確保SelectedIndex正在工作。我需要以某種方式在SQL查詢方法中使用它，我也在下面提供了這個方法。 '？'： -

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查詢方法**注意，我是從兩個不同的表拉動

凡是，我認爲我必須在'SelectedItem'中工作，但我不知道如何！

預期結果：用這三個選定字段輸出的html表。

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，真的很感謝這裏的任何幫助。我一直在爲此奮鬥超過8小時（不是開玩笑 - 我允許你笑）

Answer 1

如果我理解你的話，你想在你的WHERE條款中使用你的dropdown選定的項目。要達到此目的，請使用INNER JOIN與ON修改您的加入，然後將您的過濾條件設置爲WHERE。以下的希望代碼將有所幫助

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（）沒有工作，你可以嘗試SelectedValue

Answer 2

假設clinic_id是在數據庫中的數字字段：（否則只用單引號括起來（「」））

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; 

你也可以做這樣的：

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

請公關在vb.net

這裏奧維德代碼是我的代碼，我想從表中顯示獎金金額，其中class id爲條件：

如果class id是3，那麼獎金爲這是在我的文本框顯示名爲txtprize.text和class Id是顯示在列表框中。

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