请教数据匹配效率问题 - 专家坐堂 - Foxtable(狐表) - 新一代数据库软件，完美融合Access、Foxpro、Excel、vb.net之优势，人人都能掌握的快速软件开发工具!

Dim st As Date = Date.Now

Dim dt As DataTable = DataTables("表A")

Dim dt1 As DataTable = DataTables("表B")

dt.LoadFilter = ""
dt.Load

dt1.LoadFilter = ""
dt1.Load
MessageBox.Show("耗时: " & (Date.Now - st).TotalSeconds & "秒")
st = Date.Now
Dim w As DataRow
Dim q As Integer
dt1.AddNew(dt.Rows.Count)
For Each dr As Row In dt.Rows
    w = dt1.Find("pn = '" & dr("pn") & "'")
    If w IsNot Nothing Then
        If CDate(dr("approved")) > CDate(w("approved")) Then
            w("po") = dr("po")
            w("pi") = dr("pi")
            w("approved") = dr("approved")
            w("cost") = dr("cost")
        End If
    Else
        q = dt1.Compute("count(pn)", "pn > ''")
        w = dt1.DataRows(q)
        w("po") = dr("po")
        w("pi") = dr("pi")
        w("pn") = dr("pn")
        w("approved") = dr("approved")
        w("cost") = dr("cost")
    End If

MessageBox.Show("耗时: " & (Date.Now - st).TotalSeconds & "秒")
dt1.DeleteFor("pn is null")
dt1.Save

表A的数据大概在25000多条，表B的数据大概在4000条，现在将表A的数据与表B的保留最大日期的数值，匹配合并到表B中，上述代码发现这个红色范围区域，这个匹配需要70多秒，速度比较慢！这个还能怎么优化？

【现在将表A的数据与表B的保留最大日期的数值，匹配合并到表B中】--这个逻辑不是很理解，请详细再描述一下

以下内容为程序代码:

1 如表A
2 po pi pn approved
3 P001     1    A1        2022-06-23 12:00:00
4 P002     1    A2        2022-06-23 12:00:00
5
6
7 如表B
8 po          pi      pn approved
9 P003     1    A1        2022-06-22 12:00:00
10
11
12 处理后变成
13
14 如表A
15 po          pi      pn approved
16 P001     1    A1        2022-06-23 12:00:00
17 P002     1    A2        2022-06-23 12:00:00

就是表A的处理的表，表B是记录表，我需要在刷新时，取到处理表的记录，然后把最新的记录更新到表B中，表A的处理可能有多条不同时间的重复记录，但只保留最后一条

[此贴子已经被作者于2022/6/23 10:02:17编辑过]

还是看不懂

此主题相关图片如下：1.png

这个业务场景

取采购订单明细中最后一次采购价格及采购订单号信息

上面那个处理结果是表B的，写错了，写成表A的了

Dim cmd As New SQLCommand

cmd.ConnectionName = "数据源名称"
Dim dt As DataTable
Dim cmb As WinForm.ComboBox
cmd.CommandText = "SELECT a.* From {表A} as a inner join (select pn,max(approved) as approved from {表A} group by pn) as b on a.pn = b.pn where a.approved=b.approved"
dt = cmd.ExecuteReader()

Dim dt1 As DataTable = DataTables("表B")

Dim w As DataRow

For Each dr As Row In dt.Rows
w = dt1.Find("pn = '" & dr("pn") & "'")
If w is Nothing Then
w = dt1.addnew

w("pn") = dr("pn")
  End If
        w("po") = dr("po")
        w("pi") = dr("pi")
        w("approved") = dr("approved")
        w("cost") = dr("cost")

主题：请教数据匹配效率问题