100165613.htm
来自「C#高级编程(第三版),顶死你们。。 。up」· HTM 代码 · 共 192 行 · 第 1/3 页
HTM
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<p class="a4" style="MARGIN-LEFT: 10.7pt"><span lang="EN-US">None</span></p>
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<p class="a4" style="MARGIN-LEFT: 10.7pt"><span style="FONT-FAMILY: 宋体">删除从该命令返回的所有数据</span></p>
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<p class="a4" style="MARGIN-LEFT: 10.7pt"><span lang="EN-US">OutputParameters</span></p>
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<p class="a4" style="MARGIN-LEFT: 10.7pt"><span style="FONT-FAMILY: 宋体">命令的任何输出参数都映射到</span><span lang="EN-US">DataRow</span><span style="FONT-FAMILY: 宋体">的对应列上</span></p>
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<h4 style="FTEL: 21.45pt"><span lang="EN-GB">2. </span><span style="FONT-FAMILY: 黑体">更新现有的行</span></h4>
<p class="MsoNormal"><a ftel="rowsupdating"><span style="FONT-FAMILY: 宋体">更新</span><span lang="EN-US">DataTable</span></a><span style="FONT-FAMILY: 宋体">中一个已经存在的行只需使用带有一个列名或列号的</span><span lang="EN-US">DataRow</span><span style="FONT-FAMILY: 宋体">索引器即可</span><span style="FONT-FAMILY: 宋体">，</span><span style="FONT-FAMILY: 宋体">如下面的代码所示</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">r["RegionDescription"]="North West England";</span></p>
<p class="2" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-GB">r[1] = "North East England";</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">这两个语句是等价的</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">在本例中</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">：</span></p>
<p class="a6" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-GB">Changed RegionID 5 description</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-GB"> 1 Eastern Unchanged</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-GB"> 2 Western Unchanged</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-GB"> 3 Northern Unchanged</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-GB"> 4 Southern Unchanged</span></p>
<p class="a6" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-GB"> 5 North West England Modified</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">在更新数据库前</span><span style="FONT-FAMILY: 宋体">，</span><span style="FONT-FAMILY: 宋体">被更新的行应把其状态设置为</span><span lang="EN-US">Modified</span><span style="FONT-FAMILY: 宋体">，</span><span style="FONT-FAMILY: 宋体">其值如上所示。</span></p>
<h4 style="FTEL: 21.45pt"><span lang="EN-GB">3. </span><span style="FONT-FAMILY: 黑体">删除一行</span></h4>
<p class="MsoNormal"><a ftel="rowsdeleting"><span style="FONT-FAMILY: 宋体">删除一行需要调用</span><span lang="EN-US">Delete()</span></a><span style="FONT-FAMILY: 宋体">方法</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">r.Delete();</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">被删除的行把其行状态设置为</span><span lang="EN-US">Deleted</span><span style="FONT-FAMILY: 宋体">，</span><span style="FONT-FAMILY: 宋体">但不能从被删除的</span><span lang="EN-US">DataRow</span><span style="FONT-FAMILY: 宋体">中读取列</span><span style="FONT-FAMILY: 宋体">，</span><span style="FONT-FAMILY: 宋体">因为它们已经不再有效</span><span style="FONT-FAMILY: 宋体">，</span><span style="FONT-FAMILY: 宋体">当调用适配器的</span><span lang="EN-US">Update()</span><span style="FONT-FAMILY: 宋体">方法时，所有被删除的行都会使用</span><span lang="EN-US">DeleteCommand</span><span style="FONT-FAMILY: 宋体">，在本例中是执行</span><span lang="EN-US">RegionDelete</span><span style="FONT-FAMILY: 宋体">存储过程。</span></p></div>
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<h1 id="divCurrentNode2" style="color: #b83507; width: 100%; text-align: left; font-size: 12px; padding-left: 2px">当前章节:<a href='100165613.htm'><font color='red'>21.8.1 通过数据适配器进行更新</font></a></h1>
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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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