Question

执行我的方法（下面的代码）时出现上述异常：

Sub loadDates(ByVal newDate As Date)

    Dim dayCount As Integer = 0

    conn = New SqlConnection(connectionString)
    ds = New DataSet("Holiday")
    sql = New SqlCommand("SELECT * FROM Holiday", conn)

    Dim da As SqlDataAdapter = New SqlDataAdapter("SELECT date FROM Holiday", conn)
    conn.Open()
    da.FillSchema(ds, SchemaType.Source, "Holiday")
    da.Fill(ds, "Holiday")

    Dim tblHoliday As DataTable
    tblHoliday = ds.Tables("Holiday")

    For Each row As DataRow In tblHoliday.Rows
        If Not row Is Nothing Then
            For items As Integer = 0 To tblHoliday.Rows.Count Step 1
                Dim dateValue As Date = row.Item(0)
                If newDate = dateValue Then
                    dayCount += 1
                End If
                Exit For
            Next
        End If
    Next

    conn.Close()

    If newDate.DayOfWeek = DayOfWeek.Saturday Or newDate.DayOfWeek = DayOfWeek.Sunday Then
        dayCount = 2
    End If

    For days As Integer = dayCount To 0 Step -1
        Dim dropDates As Date = New Date(newDate.Year, newDate.Month, newDate.Day - days)
        ddDate.Items.Add(dropDates.ToShortDateString())
    Next
End Sub

我已经将问题缩小到了方法中的For Each循环内，当我输入一个日期并且它跳过循环时它没有问题。当它必须通过循环时它崩溃了：

Dim dropDates As Date = New Date(newDate.Year, newDate.Month, newDate.Day - days)

有什么想法吗？

Answer 1

减去日期而不是日期组件的天数，这样日期组件不会超出范围：

Dim dropDates As Date = New Date(newDate.Year, newDate.Month, newDate.Day).AddDays(-days)

如果newDate没有使用Date构造函数删除任何时间组件组件，则可以直接使用newDate：

Dim dropDates As Date = newDate.AddDays(-days)

Year，Month和Day参数描述方法执行中不可表示的DateTime异常

1 个答案: