摘要：
六、专题图
6种专题图：除独立值专题图绑定的字段类型可以是字符的以外，都必须是数字类型。与其
他数据源绑定时，使用ODBC
调用ThemeDlg对话框可以让用户自己定义专题图。示例：
For Each ftr In lyr.Selection
The children of the layer are the individual
features
Set ftrNode = QueryTree.Nodes.Add(lyrNode, tvwChild,lyr.Name _
& ftr.Name & Str$(ftr.FeatureID), ftr.Name)
For Each fld In ds.Fields
Each feature has data attached to it; add this data as a child of the feature
lyr.KeyField = fld.Name
QueryTree.Nodes.Add ftrNode, tvwChild, , lyr.KeyField _
& ": " & ftr.KeyValue
Next
Next