VB.NET：无法将 access 数据库中的选定数据显示到 datagridview 中

Question

我一直试图在按下按钮时将 Access 数据库中的选定数据显示到 datagridview 中，但它没有显示任何记录，也没有显示任何错误。

Dim third_da As OleDb.OleDbDataAdapter
Dim third_ds As New DataSet


Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click


    con.Open()
    Dim cb_two As New OleDb.OleDbCommandBuilder(third_da)

    query_three = "SELECT emp_timing.emp_code, emp_timing.day, emp_timing.travel_time, emp_timing.travel_dest,emp_timing.emp_timein,emp_timing.emp_timeout, emp_timing.emp_hours, emp_timing.emp_mins " & _
        "FROM emp_timing WHERE (((emp_timing.emp_code)=" & empcode & ") AND ((emp_timing.day) Like '??/" & ComboBox1.Text & "/20" & TextBox9.Text & "'))"

    ' "WHERE (((emp_timing.emp_code)=22) AND ((emp_timing.day) Like '??/05/2016'))"

    third_da = New OleDb.OleDbDataAdapter(query_three, con)

    third_da.Fill(third_ds, "ets")


    DataGridView1.DataSource = third_ds.Tables("ets")

    con.Close()
    Dim view As New DataView(third_ds.Tables(0))
    source1.DataSource = view
    DataGridView1.DataSource = view

    DataGridView1.ReadOnly = True
    DataGridView1.CancelEdit()

End Sub

提前致谢！

Answer 1

您可以像这样在查询中更改emp_timing.day 字段的条件：

(Month(emp_timing.day) = & ComboBox1.Text & 
                   and Year(emp_timing.day) = "20" & TextBox9.Text & " )

但是，我建议你使用 Parameter 来避免 SQL 注入，如下所示：

query_three = "SELECT emp_timing.emp_code, emp_timing.day, emp_timing.travel_time, emp_timing.travel_dest,emp_timing.emp_timein,emp_timing.emp_timeout, emp_timing.emp_hours, emp_timing.emp_mins " &
"FROM emp_timing WHERE (((emp_timing.emp_code)= @empcode) AND ((emp_timing.day) BETWEEN @startDate AND @endDate ))"

Dim startDate As New DateTime("20" & TextBox9.Text, ComboBox1.Text, 1)
Dim endDate As DateTime = startDate.AddMonths(1).AddDays(-1)

Dim cmd As New OleDbCommand(query_three, con)
cmd.Parameters.AddWithValue("@empcode", empcode)
cmd.Parameters.AddWithValue("@startDate", startDate.ToString("#yyyy/MM/dd#"))
cmd.Parameters.AddWithValue("@endDate", endDate.ToString("#yyyy/MM/dd#"))
third_da = New OleDb.OleDbDataAdapter(cmd)