Question

我意识到这已被问了一百万次，但我找不到有效的答案。新的sql server和vs vb（抱怨老板，不是我），做练习跑。在以下内容中继续将varchar转换为数字异常：

Dim height, width As Decimal

        height = InputBox("Enter height:")
        width = InputBox("Enter width:")

        'PRODUCING VARCHAR TO NUMERIC EXCEPTION
        command = New SqlCommand("DECLARE @height as decimal(10,2), " & _
                                 "@width as decimal(10,2), " & _
                                 "@area as decimal(10,2); " & _
                                 "SET @height = ' " & height & " '; " & _
                                 "SET @width = ' " & width & " '; " & _
                                 "SET @area = @height * @width; " & _
                                 "IF @height IS NULL OR @width IS NULL " & _
                                 "     SELECT 'Either the height or width field was blank.' " & _
                                 "ELSE IF @height <= 0 OR @width <= 0 " & _
                                 "     SELECT 'That''s some fancy negative space.' " & _
                                 "ELSE " & _
                                 "     SELECT 'The area is: ' +@area;" _
                                 , connect)
        connect.Open()
        rdr = command.ExecuteReader()

我已经通过vartype（）验证了传递的数据确实是十进制的（我是唯一一个测试，因此不担心错误控制atm）。我尝试使用带有和不带有单引号的变量。 Cast（）和Convert（）不起作用（除非我做错了吗？）。不确定问题出在哪里？

Answer 1

Dim height, width As Decimal
height = InputBox("Enter height:")
width = InputBox("Enter width:")

'PRODUCING VARCHAR TO NUMERIC EXCEPTION
command = New SqlCommand("IF @height IS NULL OR @width IS NULL " & _
                         "     SELECT 'Either the height or width field was blank.' " & _
                         "ELSE IF @height <= 0 OR @width <= 0 " & _
                         "     SELECT 'That''s some fancy negative space.' " & _
                         "ELSE " & _
                         "     SELECT 'The area is: ' + cast(@width * @height as varchar(20))" _
                    , connect)

command.Parameters.Add("@height", SqlDbType.Decimal).Value = height
command.Parameters.Add("@width", SqlDbType.Decimal).Value = width
connect.Open()
rdr = command.ExecuteReader()

另外，在SQL中编写IF / ELSE语句以在各种选择中进行选择非常奇怪。对于SQL，您希望考虑编写描述一组数据的单个语句。

Varchar到数字异常

1 个答案: