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21.2.2 事务处理
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C#高级编程（第3版）
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21.2.2 事务处理
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2006-10-13 14:41:00
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<div style='float:left;width:49%'>·<a href='100165595.htm'>21.1.3 数据库特定的类</a></div><div style='float:right;width:49%'>·<a href='100165596.htm'>21.2 使用数据库连接</a></div><div style='float:left;width:49%'>·<a href='100165597.htm'>21.2.1 高效地使用连接</a></div><div style='float:right;width:49%'>·<a href='100165599.htm'>21.3 命令</a></div><div style='float:left;width:49%'>·<a href='100165600.htm'>21.3.1 执行命令</a></div><div style='float:right;width:49%'>·<a href='100165601.htm'>21.3.2 调用存储过程</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="_Toc507815159"><span lang="EN-US">21.2.2 </span></a><span style="FONT-FAMILY: 黑体">事务处理</span></h3>
<p class="MsoNormal" style="LINE-HEIGHT: 15pt"><a ftel="transactions"><span style="FONT-FAMILY: 宋体">通常，对数据库要进行多次更新，这些更新必须在事务处理的范围内进行。</span><span lang="EN-US">ADO.NET</span></a><span style="FONT-FAMILY: 宋体">中的事务处理首先要在数据库连接对象上调用</span><span lang="EN-US">BeginTransaction()</span><span style="FONT-FAMILY: 宋体">方法，这些方法返回实现</span><span lang="EN-US">IDbTransaction</span><span style="FONT-FAMILY: 宋体">接口的对象，而该对象是在</span><span lang="EN-US">System.Data</span><span style="FONT-FAMILY: 宋体">中定义的。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 15pt"><span style="FONT-FAMILY: 宋体">下面的代码序列是在</span><span lang="EN-US">Sql Server</span><span style="FONT-FAMILY: 宋体">连接上开始事务处理的：</span></p>
<p class="a6" style="MARGIN-TOP: 6.5pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-GB">string source = "server=(local)\\NetSDK;" +</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-GB"> "</span><span lang="EN-GB"> </span><span lang="EN-GB">integrated security=SSPI;" + </span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-GB"> "database=Northwind";</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-GB">SqlConnection conn = new SqlConnection(source);</span></p>
<p class="a6" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-GB">conn.Open();</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-GB">SqlTransaction tx = conn.BeginTransaction();</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-GB"> </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-GB">// Execute some commands, then commit the transaction</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-GB"> </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-GB">tx.Commit();</span></p>
<p class="a6" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-GB">conn.Close();</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 15pt"><span style="FONT-FAMILY: 宋体; LETTER-SPACING: 0.1pt">在开始一个事务处理时，可以选择在该事务处理中执行的命令独立级别。该级别确定了如何在一个数据库会话中查看在另一个数据库会话中所进行的修改，并不是所有的数据库引擎都支持表</span><span lang="EN-US" style="LETTER-SPACING: 0.1pt">21-1</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: 0.1pt">所示的</span><span lang="EN-US" style="LETTER-SPACING: 0.1pt">4</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: 0.1pt">个级别。</span></p>
<p class="a5" style="MARGIN-TOP: 4.9pt"><a ftel="isolationlevels"><span style="FONT-FAMILY: 黑体">表</span></a><span lang="EN-GB"> 21-1</span></p>
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<p class="a2" style="LINE-HEIGHT: 15.6pt"><span style="FONT-FAMILY: 黑体">独</span> <span style="FONT-FAMILY: 黑体">立</span> <span style="FONT-FAMILY: 黑体">级</span> <span style="FONT-FAMILY: 黑体">别</span></p>
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<p class="a2" style="LINE-HEIGHT: 15.6pt"><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; LINE-HEIGHT: 15.6pt"><span lang="EN-US">ReadCommitted</span></p>
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