要用这种方法
Dim Cols1() As String = {"来源列一","来源列二","来源列三"}
Dim Cols2() As String = {"接收列一","接收列二","接收列三"}
For Each dr1 As DataRow In DataTables("表A").Select("")
Dim dr2 As DataRow = DataTables("表B").find("第一列 = '" & dr1("第一列") & "' and 第二列 = '" & dr1("第二列") & "' and 第三列 = '" & dr1("第三列") & "'")
If dr2 Is Nothing Then
dr2 = DataTables("表B").AddNew()
End If
For i As Integer = 0 To Cols1.Length -1
dr2(Cols2(i)) = dr1(Cols1(i))
Next
Next