Take combobox SelectedIndex data and use in SELECT Query - VB.net - sql

Question

I'm a little desperate, hence why I'm here! I'm quite new to programming and have been given an assignment where I need to use a range of SQL queries to generate a simple HTML report table. There is also a user input, with them selecting the ClinicID from the comboBox and clicking a button to generate the report.
Basically, I have a comboBox that I have populated with 'ClinicID', as below. I have also made sure that SelectedIndex is working. I need to somehow use this in the SQL query method which I have also provided below.
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 query method - **note, I'm pulling from two different tables:
Where the '?' is, is where I assume I have to work in the 'SelectedItem' but I have no idea how!
Desired result: an html table outputted with these three selected fields.
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
Really, really appreciate any help here. Ive been struggling with this for more than 8 hours (not joking - I give you permission to laugh)

Answer 1

If i understand you correctly, you want to use your dropdown selected item in your WHERE clause. To achieve that , revise your joining using INNER JOIN with ON then place your filtering in WHERE condition. Hope code below will help.
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
if the selectedItem.ToString() did not work, you can try SelectedValue

Answer 2

Assuming that clinic_id is a numeric field in the database: (otherwise just surround it with single quotes (''))
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;
You can also do it like this:
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

Please provide code in vb.net
Here is my code, I want to display prize amount from table where class id is condition :
If class id is 3 then prize for that is display in my textbox named txtprize.text and class Id is displayed in list box.
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