With regards to another thread, http://www.daniweb.com/forums/thread251069.html on how to compare the current date to retrieve relevant data (Details there), now I have issue on storing this query result on a VB.net variable.
It works in this way. It is an academic work to do a ecommerce website, and I need to compute some tax imposed on the goods purchased. Relevant subtotal etc has been implemented except on computing the tax. It is supposed to be a function and I have coded it in this way:
Public Function computeTaxCharge(ByVal dblSubTotal As Double) As Double
Dim dblTaxRate As Double
Dim dblTaxCharge As Double
Dim strConn As String
strConn = ConfigurationManager.ConnectionStrings("AppDb").ToString
Dim conn As New SqlConnection(strConn)
Dim strSql As String
strSql = "SELECT Top 1 TaxRate" & _
"FROM GST" & _
"WHERE EffectiveDate <= @dt" & _
"ORDER BY EffectiveDate DESC"
' Define an Command object to execute the SQL statement
Dim cmd1 As New SqlCommand(strSql, conn)
cmd1.Parameters.AddWithValue("@Dt", System.DateTime.Now())
' Open database connection
conn.Open()
' Execute the Insert SQL
cmd1.ExecuteNonQuery()
' Define a data adapter to fetch data
Dim da As New SqlDataAdapter(cmd1)
'Create a dataset
Dim ds As New DataSet
' Fetch data to a table
da.Fill(ds, "dblTaxRate")
' Define a data table to hold the data fetched
Dim dt As New DataTable
' Close database connection
conn.Close()
dblTaxCharge = dblSubTotal * dblTaxRate / 100
Return dblTaxCharge
End Function
But it crashes on
da.Fill(ds,"dblTaxRate")
.
How should I do? Thank you in advance.