将数据类型 varchar 转换为数字 vb.net 时出错

Question

当我尝试将数据插入数据库时​​，出现错误，称为“将数据类型 varchar 转换为数字时出错”

这是我的代码

objcon.DoExecute("INSERT INTO OrderItemF 
                  VALUES('" & dgOrder.Item("Item No", i).Value & "'
                         ,'"& dgOrder.Item("Item Type", i).Value & "'
                         ,'" & txtOdrNo.Text & "'
                         ,'" & dgOrder.Item("Unit Price", i).Value & "'
                         ,'" & dgOrder.Item("Quantity", i).Value & "'
                         ,'" & dgOrder.Item("Discount", i).Value & "'
                         ,'" & dgOrder.Item("Total Value", i).Value & 
                        "')"
                       )

我正在从名为 dgorder 的数据网格查看器中插入数据

Answer 1

你的问题是当你这样做时

"'" & dgOrder.Item("Unit Price", i).Value & "'"

对于数字，您的查询将类似于 'value'。但是对于数字，您不需要单引号。所以你需要做的是删除你有数值的单引号。

这是你的数据库在抱怨 - “我期望整数，而你给了我一个字符串”

编辑

我的原始答案解决了您的插入问题。现在，您需要对null 值、数据中可能的单引号以及将文本转换为null 做更多的工作

dim itemNum as string = dgOrder.Item("Item No", i).Value ' assume it is string
itemNum  = If(string.IsNullOrEmpty(itemNum), "NULL", "'" & itemNum.Replace("'", "''") & "'") 

dim itemType as string = dgOrder.Item("Item Type", i).Value ' assume it is string
itemType = If(string.IsNullOrEmpty(itemType), "NULL", "'" & itemType.Replace("'", "''") & "'") 

dim orderNum as string = If(string.IsNullOrEmpty(txtOrdNo.Text), "NULL", "'" & itemType.Replace("'", "''") & "'") 

dim decVal as Decimal
dim intVal as Decimal
dim unitPrice as string = If(dgOrder.Item("Unit Price", i).Value, "") ' assume it is decimal
if Decimal.TryParse(unitPrice, decVal) Then
    Throw New Exception("Invalid Unit Price")
Else
   unitPrice = decVal.ToString()
End If                 

dim quantity as string = If(dgOrder.Item("Quantity", i).Value, "") ' assume it is integer
if Integer.TryParse(unitPrice, intcVal) Then
    Throw New Exception("Invalid Quantity")
Else
    quantity = intVal.ToString()
End If          

dim discount as string = If(dgOrder.Item("Discount", i).Value, "0") ' assume it is decimal
if Decimal.TryParse(discount, decVal) Then
    Throw New Exception("Invalid Discount")
Else
   discount = decVal.ToString()
   ' may need: discount = If(decVal = 0, "NULL", decVal.ToString())
End If 

dim total as string = If(dgOrder.Item("Total Value", i).Value, "") ' assume it is decimal
if Decimal.TryParse(total, decVal) Then
    Throw New Exception("Invalid Total Value")
Else
   total = decVal.ToString()
End If                          

dim sql as String = String.Format("INSERT INTO OrderItemF VALUES({0},{1},{2},{3},{4},{5},{6})",
    itemNum, itemType, orderNum, unitPrice, quantity, discount, total)

objcon.DoExecute(sql)

这更像是编程