标题：令人目瞪口呆的效率差别(有修正)

这个鱼和熊掌不可得兼的经验，收藏！

有一按钮“编号”：自觉效率不高，能优化？

Dim str As String
For Each dr As DataRow In DataTables("申请表").DataRows
    str = "[乡名] = '" & dr("乡名") & "'And [村名] = '" & dr("村名") & "' And [组别] = '" & dr("组别") & "'"
    str = str  & "And  [单位(个人)] = '" & dr("单位(个人)") & "'  And  [法定代表人] = '" & dr("法定代表人") & "' And [_Identify] < " & dr("_Identify")
    dr("宗地序号") = Format(Tables("申请表").Compute("Count(乡名)",str)+1,"00")
Next
Tables("申请表").Sort = "法定代表人 DESC" '降序排列

添加到集合再对比，真是高。受用了。

顶！试试去

可以这么改改看看：

Dim str As String
Dim Dic As New Dictionary(of DataRow, String)
For Each dr As DataRow In DataTables("申请表").DataRows
    str = "[乡名] = '" & dr("乡名") & "'And [村名] = '" & dr("村名") & "' And [组别] = '" & dr("组别") & "'"
    str = str  & "And  [单位(个人)] = '" & dr("单位(个人)") & "'  And  [法定代表人] = '" & dr("法定代表人") & "' And [_Identify] < " & dr("_Identify")
    dic.Add(dr,Format(DataTables("申请表").Compute("Count(乡名)",str)+1,"00"))
Next
For dr As DataRow In dic.Keys
    dr("宗地序号") = dic(dr)
Next

这都看不出来吗，我手误而已， 应该是：

For Each dr As DataRow In dic.keys