CODEWITHSUNDEEP
vb.netwinforms
Jarobe Bernardo
Jarobe Bernardo

Reputation: 75

putting data from database to label.text

When I call setText method it wont return anything. 

setText("Sprite", "lblSpriteQty.Text", "lblSpriteTP.Text", 15)

Code I use for method setText

 Public Sub setText(ByVal productname As String, ByVal qty As String, ByVal tp As String, ByVal price As Integer)

    Using cs As New SqlConnection("Data Source=KARL-PC;Initial Catalog=ShawarmaToldb;Integrated Security=True")
        Using cmd As New SqlCommand("SELECT SUM(quantity) FROM [tblOrderDetails] WHERE productid = (SELECT productid FROM [tblProduct] WHERE productname = @productname)", cs)
            cmd.Parameters.AddWithValue("@productname", productname)
            cmd.CommandType = CommandType.Text
            cs.Open()
            cmd.ExecuteNonQuery()
            Dim dr As SqlDataReader = cmd.ExecuteReader()
            While dr.Read()
                If IsDBNull(dr.GetValue(0)) Then
                    qty = "0" 'but if i put lblSpriteQty.Text instead of qty it's working
                    tp = "0" 'same as here
                Else
                    qty = dr.GetValue(0).ToString
                    tp = dr.GetValue(0).ToString * price
                End If
            End While
        End Using
    End Using
End Sub

Upvotes: 0

Views: 104

Answers (1)

Tim Schmelter
Tim Schmelter

Reputation: 460138

You are modifying local variables(the method arguments) instead of returning qty and tp to the calling method. But even if you made them ByRef you couldn't change them since strings are immutable. Instead either set the text in this method or make it a Function that returns an Integer for the quantity which is all that you need.

Public Function GetSumQuantity(ByVal productname As String) As Integer
    Using cs As New SqlConnection("Data Source=KARL-PC;Initial Catalog=ShawarmaToldb;Integrated Security=True")
        Using cmd As New SqlCommand("SELECT SUM(quantity) FROM [tblOrderDetails] WHERE productid = (SELECT productid FROM [tblProduct] WHERE productname = @productname)", cs)
            cmd.Parameters.AddWithValue("@productname", productname)
            cs.Open()
            Dim sumQuantityObj = cmd.ExecuteScalar()
            If DbNull.Value = sumQuantityObj Then Return 0
            Return DirectCast(sumQuantityObj, Integer)
        End Using
    End Using
End Sub

Now you can calculate the value and assign it to the label's text in the calling method:

Dim sumQuantity As Integer = GetSumQuantity("IPhone")
Dim tp = price * sumQuantity 
lblSpriteQty.Text = tp.ToString()

Upvotes: 1

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