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21.8.1 通过数据适配器进行更新
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C#高级编程（第3版）
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21.8.1 通过数据适配器进行更新
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2006-10-13 14:41:00
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<div style='float:left;width:49%'>·<a href='100165610.htm'>21.7.1 用数据适配器来填充 DataSet</a></div><div style='float:right;width:49%'>·<a href='100165611.htm'>21.7.2 从XML中给数据集填充数据</a></div><div style='float:left;width:49%'>·<a href='100165612.htm'>21.8 保存对数据集的修改</a></div><div style='float:right;width:49%'>·<a href='100165614.htm'>21.8.2 写入XML输出结果</a></div><div style='float:left;width:49%'>·<a href='100165615.htm'>21.9 使用ADO.NET</a></div><div style='float:right;width:49%'>·<a href='100165616.htm'>21.9.1 分层开发</a></div></div>
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<span lang="EN-GB">21.8.1 </span><span style="FONT-FAMILY: 黑体">通过数据适配器进行更新</span></h3>
<p class="MsoNormal"><a ftel="dataadapters2"><span style="FONT-FAMILY: 宋体">除了</span><span lang="EN-US">SqlDataAdapter</span></a><span style="FONT-FAMILY: 宋体">最有可能包含的</span><span lang="EN-US"> SelectCommand</span><span style="FONT-FAMILY: 宋体">之外</span><span style="FONT-FAMILY: 宋体">，</span><span style="FONT-FAMILY: 宋体">还可以定义</span><span lang="EN-US">InsertCommand</span><span style="FONT-FAMILY: 宋体">、</span><span lang="EN-US"> UpdateCommand </span><span style="FONT-FAMILY: 宋体">和</span><span lang="EN-US"> DeleteCommand</span><span style="FONT-FAMILY: 宋体">。顾名思义</span><span style="FONT-FAMILY: 宋体">，</span><span style="FONT-FAMILY: 宋体">这些对象都是适用于相应提供程序的命令对象</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">例如</span><span lang="EN-US">SqlCommand </span><span style="FONT-FAMILY: 宋体">或</span><span lang="EN-US"> OleDbCommand)</span><span style="FONT-FAMILY: 宋体">实例。</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">有了这种灵活性后，就可以自由调整应用程序，对频繁使用的命令</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">例如</span><span lang="EN-US">select</span><span style="FONT-FAMILY: 宋体">和</span><span lang="EN-US">insert)</span><span style="FONT-FAMILY: 宋体">采用合适的存储过程来执行，对不常使用的命令</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">例如</span><span lang="EN-US">delete)</span><span style="FONT-FAMILY: 宋体">采用</span><span lang="EN-US">SQL</span><span style="FONT-FAMILY: 宋体">命令的方式执行。一般应为所有的数据库交互操作提供存储过程，因为这会更快，更容易调整。</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">本节的示例重新使用“调用存储过程”一节中的存储过程，插入、更新和删除</span><span lang="EN-US">Region</span><span style="FONT-FAMILY: 宋体">记录，再把这些与上面编写的</span><span lang="EN-US">RegionSelect</span><span style="FONT-FAMILY: 宋体">过程结合起来，生成一个新示例，这个示例使用这些命令来检索和更新</span><span lang="EN-US">DataSet</span><span style="FONT-FAMILY: 宋体">中的代码。代码的主体如下所示。</span></p>
<h4 style="FTEL: 21.45pt"><span lang="EN-GB">1. </span><span style="FONT-FAMILY: 黑体">插入一个新行</span></h4>
<p class="MsoNormal"><a ftel="rowsinserting"><span style="FONT-FAMILY: 宋体">把新行添加到</span><span lang="EN-US">DataTable</span></a><span style="FONT-FAMILY: 宋体">中有两种方式。第一种方式是调用</span><span lang="EN-US">NewRow()</span><span style="FONT-FAMILY: 宋体">函数</span><span style="FONT-FAMILY: 宋体">，</span><span style="FONT-FAMILY: 宋体">返回一个空行</span><span style="FONT-FAMILY: 宋体">，</span><span style="FONT-FAMILY: 宋体">然后向其填充数据</span><span style="FONT-FAMILY: 宋体">，</span><span style="FONT-FAMILY: 宋体">最后把它添加到</span><span lang="EN-US">Rows</span><span style="FONT-FAMILY: 宋体">集合中</span><span style="FONT-FAMILY: 宋体">：</span></p>
<p class="2" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-GB">DataRow r = ds.Tables["Region"].NewRow();</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-GB">r["RegionID"]=999;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-GB">r["RegionDescription"]="North West";</span></p>
<p class="2" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-GB">ds.Tables["Region"].Rows.Add(r);</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">第二种方式是把一组数据传送给</span><span lang="EN-US">Rows.Add()</span><span style="FONT-FAMILY: 宋体">方法：</span></p>
<p class="2" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-GB">DataRow r = ds.Tables["Region"].Rows.Add </span></p>
<p class="2" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-GB"> (new object [] { 999 , "North West" });</span></p>
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