关于读取XML

Question

XML格式如下：　<?xml version="1.0" standalone="yes"?>
<DocumentElement>
  <Sheet>
    <Catalog>01</Catalog>
    <TableName>01-ASIC</TableName>
    <SearchField>Part Type</SearchField>
    <SearchField>IC Package</SearchField>
    <SearchField>PCB Footprint</SearchField>
    <Specification>PCB Footprint</Specification>
    <Specification>Maker</Specification>
    <Specification>Maker Part Number</Specification>
</Sheet>
  <Sheet>
    <Catalog>02</Catalog>
    <TableName>02-Memory IC</TableName>
    <SearchField>Part Type</SearchField>
    <SearchField>Address Access Time (Unit : ns)</SearchField>
    <SearchField>Package</SearchField>
    <SearchField>PCB Footprint</SearchField>
    <Specification>PCB Footprint</Specification>
    <Specification>Maker</Specification>
    <Specification>Maker Part Number</Specification>
  </Sheet>
  <Sheet>
    <Catalog>06</Catalog>
    <TableName>06-Virtual Capacitance</TableName>
    <Specification>Value</Specification>
    <Specification>Temperature Characteristics</Specification>
  </Sheet>
</DocumentElement>
采用ReadXml()读取，数据存放到Dataset中便是三个表，格式分别如下：
表一：
Catalog　TableName01　　　　01-ASIC
02　　　　02-Memory IC
06　　　　06-Virtual Capacitance表二：
SearchField_textPart Type
IC Package
PCB Footprint
Part Type
Address Access Time (Unit : ns)
Package
PCB Footprint表三：
Specification_textPCB Footprint
Maker
Maker Part Number
PCB Footprint
Maker
Maker Part Number
Value
Temperature Characteristics现在问题是：怎么在这三个表之间建立关系呢？关系如下，当我读取“表一”的“01”时，那么“表二”的“Part Type”，“IC Package”，“PCB Footprint”以及“表三”的“PCB Footprint”，“Maker”，“Maker Part Number”的内容也能够同时获取。
静候佳音......