Question

请任何人帮助我，我只是制作一个微型金融类型的软件，有一个问题我想每周显示从访问数据库到vb.net数据网格视图的数据，但不能正常工作我的代码，

我插入EntryDate Savings Entry Lable Date（lblSavingsEntryDate.Text = Date.Now.ToString（＆＃34; dd / MM / yyyy＆＃34;））

这是我的代码

Private Sub btnBalanceWeekly_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnBalanceWeekly.Click

    Dim Sunday = DateTime.Now.AddDays((Today.DayOfWeek - DayOfWeek.Sunday) * -1).ToString("dd/MM/yyyy")
    Dim todate = DateTime.Now.AddDays(0).ToString("dd/MM/yyyy")
    Try
        Dim sqlstr1 As String
        sqlstr1 = "SELECT * FROM Receivedtbl WHERE  EntryDate BETWEEN '" + Sunday + "' And '" + todate + "'"
        Dim da As New OleDbDataAdapter(sqlstr1, conn2)
        Dim dt As New DataTable("Receivedtbl")
        da.Fill(dt)
        dgvBalanceSavings.DataSource = dt
    Catch ex As Exception
        MessageBox.Show(ex.Message)
    Finally
        conn2.Close()
        Me.BalanceTotalSeavings()
        Me.BalanceGrpReceived()
        Me.BalanceCusReceived()
    End Try
End Sub

请帮助...如何在每周显示数据。

Answer 1

使用Parameters（DataAdapter将以正确的方式转换date，datetime格式在sql中）而不是将date转换为更安全更安全的方式string，特别是因为不同的日期格式和避免sql注入。 Bellow就是使用Parameters，例如源格式（在本例中为date数据类型）的示例：

Private Sub btnBalanceWeekly_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnBalanceWeekly.Click

    Dim Sunday = DateTime.Now.AddDays((Today.DayOfWeek - DayOfWeek.Sunday) * -1)
    Dim todate = DateTime.Now.AddDays(0)
    Try
        Dim sqlstr1 As String
        sqlstr1 = "SELECT * FROM Receivedtbl WHERE EntryDate BETWEEN @sunday AND @todate;"
        Dim da As New OleDbDataAdapter(sqlstr1, conn2)
        da.SelectCommand.Parameters.AddWithValue("@sunday", Sunday)
        da.SelectCommand.Parameters.AddWithValue("@todate", todate)
        Dim dt As New DataTable("Receivedtbl")
        da.Fill(dt)
        dgvBalanceSavings.DataSource = dt
    Catch ex As Exception
        MessageBox.Show(ex.Message)
    Finally
        conn2.Close()
        Me.BalanceTotalSeavings()
        Me.BalanceGrpReceived()
        Me.BalanceCusReceived()
    End Try
End Sub

通过这种方式，您无需担心date格式转换。

Answer 2

您尝试将日期（字符串日期）比较为“dd / MM / yyyy”格式，并且您遇到了一个大问题，因为您的查询在运行时将是这样的：

在哪里EntryDate BETWEEN '11 / 201/2018'和'12 / 02/2018'

结果：大量字符串在这些日期之间

例如：'11 / 02/2018'，'11/03/201'，'11/04/201'，甚至是'11 / 02/2019'的另一年

在字符串比较中，早期字符总是首先进行比较，它们在比较系统中更为重要（在这种情况下，您的4个字符的年份优先级低于月份甚至白天）

解决方案：

使用此格式保存日期：

的ToString（ “YYYY / MM / DD”）

所以你的代码应该是这样的：

Private Sub btnBalanceWeekly_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnBalanceWeekly.Click

    Dim Sunday = DateTime.Now.AddDays((Today.DayOfWeek - DayOfWeek.Sunday) * -1).ToString("yyyy/MM/dd")
    Dim todate = DateTime.Now.AddDays(0).ToString("yyyy/MM/dd")
    Try
        Dim sqlstr1 As String
        sqlstr1 = "SELECT * FROM Receivedtbl WHERE  EntryDate BETWEEN '" + Sunday + "' And '" + todate + "'"
        Dim da As New OleDbDataAdapter(sqlstr1, conn2)
        Dim dt As New DataTable("Receivedtbl")
        da.Fill(dt)
        dgvBalanceSavings.DataSource = dt
    Catch ex As Exception
        MessageBox.Show(ex.Message)
    Finally
        conn2.Close()
        Me.BalanceTotalSeavings()
        Me.BalanceGrpReceived()
        Me.BalanceCusReceived()
    End Try
End Sub

但请记住，您也需要使用此格式保存日期字符串（已保存在数据库中的旧日期）

Answer 3

首先永远打开Option Strict。编译时错误 - 好，你可以修复它们。运行时错误很糟糕，你可能无法捕获它们。向表单和适当的标签添加两个DateTimePicker控件。如果默认值不适合您，可以设置各种属性。以下代码显示如何使用SQL字符串的参数。这不仅可以节省您编写字符串的麻烦，还可以保护您的数据库免受恶意输入。

Private Sub GetSavings()
        Dim da As New OleDbDataAdapter
        Dim strSQL As String = "SELECT * FROM Receivedtbl WHERE EntryDate BETWEEN @FromDate And @ToDate;"
        Dim FromDate As Date = DateTimePicker1.Value.Date
        Dim ToDate As Date = DateTimePicker2.Value.Date
        If FromDate >= ToDate Then
            MessageBox.Show("From date must be earlier than To date.")
            Exit Sub
        End If
        Dim cmd As New OleDbCommand With {
            .Connection = conn2,
            .CommandType = CommandType.Text,
            .CommandText = strSQL}
        'Access cares not about the parameter names but about there order
        cmd.Parameters.Add("@FromDate", OleDbType.Date).Value = FromDate
        cmd.Parameters.Add("@ToDate", OleDbType.Date).Value = ToDate
        da.SelectCommand = cmd
        'now continue with your .Fill code
End Sub

每周数据显示

3 个答案: