我无法在文本框中添加值。每次售票时,我都会将总价格放在一个文本框中,每次为同一个音乐会销售一张票时,它会通过将其自身添加到总价中而增加。它在第一次销售时有效,但在此之后它就崩溃了。这里是代码,并提前感谢。无法在结果集索引中找到指定的列索引超出范围索引超出范围
Private Function DisplayMoneyTaken() As Integer
Dim totalMoney As Integer
'open the database connection
strSQL = "SELECT MAX(Total_Money) FROM Sales WHERE Concert_Id =" + Mid(cboVenue.Text, 1, 4)
conn.Open()
cmd.Connection = conn
cmd.CommandText = strSQL
cmd.CommandType = CommandType.Text
dr = cmd.ExecuteReader()
'read the record returned
dr.Read()
If IsDBNull(dr.Item(0)) Then
totalMoney = txtPrice.Text
Else
DisplayMoneyTaken = dr.Item("Total_Money") + Val(txtPrice.Text)
End If
'close the database
conn.Close()
Return totalMoney
End Function