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21.5.4 数据约束
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C#高级编程（第3版）
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21.5.4 数据约束
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2006-10-13 14:41:00
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<div style='float:left;width:49%'>·<a href='100165604.htm'>21.5.1 数据表</a></div><div style='float:right;width:49%'>·<a href='100165605.htm'>21.5.2 数据列</a></div><div style='float:left;width:49%'>·<a href='100165606.htm'>21.5.3 数据关系</a></div><div style='float:right;width:49%'>·<a href='100165608.htm'>21.6 XML模式</a></div><div style='float:left;width:49%'>·<a href='100165609.htm'>21.7 填充数据集</a></div><div style='float:right;width:49%'>·<a href='100165610.htm'>21.7.1 用数据适配器来填充 DataSet</a></div></div>
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<link href="css.css" rel="stylesheet" type="text/css" /><h3 style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 0cm; MARGIN-RIGHT: 0cm; FTEL: 8.15pt"><a ftel="_Toc507815167"><span lang="EN-GB">21.5.4 </span></a><span style="FONT-FAMILY: 黑体">数据约束</span></h3>
<p class="MsoNormal" style="LINE-HEIGHT: 16pt"><a ftel="dataconstraints"><span lang="EN-US">DataTable</span></a><span style="FONT-FAMILY: 宋体">擅长于改变在客户机上创建的列的数据类型。</span><span lang="EN-US">ADO.NET</span><span style="FONT-FAMILY: 宋体">允许在列上创建一些约束，对数据应用一些规则。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 16pt"><span style="FONT-FAMILY: 宋体">运行库目前支持表</span><span lang="EN-US">21-7</span><span style="FONT-FAMILY: 宋体">所示的约束类型，它们包含在</span><span lang="EN-US">System.Data</span><span style="FONT-FAMILY: 宋体">命名空间的类中。</span></p>
<p class="a5" style="MARGIN-TOP: 8.15pt" align="center"><span style="FONT-FAMILY: 黑体">表</span><span lang="EN-US"> 21-7</span></p>
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<p class="a2"><span style="FONT-FAMILY: 黑体">约</span><span lang="EN-US"> </span><span style="FONT-FAMILY: 黑体">束</span></p>
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<p class="a2"><span style="FONT-FAMILY: 黑体">说</span><span lang="EN-US"> </span><span style="FONT-FAMILY: 黑体">明</span></p>
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<p class="a4" style="MARGIN-LEFT: 10.7pt"><a ftel="keys"><span lang="EN-US">ForeignKeyConstraint</span></a></p>
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<p class="a4" style="MARGIN-LEFT: 10.7pt"><span style="FONT-FAMILY: 宋体">在</span><span lang="EN-US">DataSet</span><span style="FONT-FAMILY: 宋体">的两个</span><span lang="EN-US">DataTable</span><span style="FONT-FAMILY: 宋体">之间建立链接</span></p>
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<p class="a4" style="MARGIN-LEFT: 10.7pt"><span lang="EN-US">UniqueConstraint</span></p>
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<p class="a4" style="MARGIN-LEFT: 10.7pt"><span style="FONT-FAMILY: 宋体">确保给定的列是惟一的</span></p>
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