处理表B

Dim pdr As DataRow = Nothing
For Each dr As DataRow In DataTables("表B").Select("姓名 is not null", "_Sortkey")
    If dr.IsNull("工资") Then
        pdr = dr
    Else
        dr("第三列") = pdr("姓名")
    End If
Next

查询表A

Dim pdr As DataRow = Nothing
For Each dr As DataRow In DataTables("表A").Select("姓名 is not null", "_Sortkey")
    If dr("姓名") Like "第*" Then
        pdr = dr
    Else
        Dim fdr As DataRow = DataTables("表B").Find("姓名 = \'" & dr("姓名") & "\' and 第三列 = \'" & pdr("姓名") & "\'")
        If fdr IsNot Nothing
            dr("第三列") = pdr("姓名")
            dr("工资") = fdr("工资")
        End If
    End If
Next