小编Jos*_*rza的帖子

我有以下代码执行查询并返回结果.但是,我环顾四周并找到一些例子来处理空值,但是我收到一个错误:"当没有数据存在时无效的读取尝试." 我也得到了错误:"从类型'DBNull'转换为'Decimal'类型无效."

有人可以帮我解决这个代码,以防止空值崩溃我的程序？

Private Sub EFFICIENCY_STACKRANK_YTD(ByVal EMPLOYEE As String)

    Dim queryString As String = "SELECT " & _
    " (SELECT CAST(SUM(TARGET_SECONDS) AS DECIMAL)/ CAST(SUM(ROUTE_SECONDS) AS DECIMAL) FROM dbo.APE_BUSDRIVER_MAIN WITH(NOLOCK) WHERE APE_AREA_OBJID = " & lblAreaOBJID.Text & " AND EMPLOYEE_NAME = '" & EMPLOYEE & "' AND YEAR_TIME = '" & cbYear.Text & "' AND ACTIVE = 1) AS RESULT1" & _
    " FROM dbo.APE_BUSDRIVER_MAIN "


    Using connection As New SqlConnection(SQLConnectionStr)
        Dim command As New SqlCommand(queryString, connection)
        connection.Open()
        Dim reader As …