MyBatis获取数据库自生成的主键Id详解及实例代码
<p><strong>MyBatis获取数据库自生成的主键Id详解及实例代码</strong></p>
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在使用MySQL数据库时我们一般使用数据库的自增主键自动产生主键。如果在插入主表时，我们需要同时插入从表的数据，这时我们通常需要知道主表插入时自动产生的主键Id值。</p>
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下面介绍使用MyBatis进行插入时，如何同时获取数据库自生成的主键：</p>
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<strong>1、XML配置文件</strong></p>
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<code class="xml plain"><</code><code class="xml keyword">insert</code> <code class="xml color1">id</code><code class="xml plain">=</code><code class="xml string">"insert"</code> <code class="xml color1">parameterType</code><code class="xml plain">=</code><code class="xml string">"Person"</code> <code class="xml color1">useGeneratedKeys</code><code class="xml plain">=</code><code class="xml string">"true"</code> <code class="xml color1">keyProperty</code><code class="xml plain">=</code><code class="xml string">"id"</code><code class="xml plain">></code>
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<code class="xml spaces"> </code><code class="xml plain">insert into person(name,pswd) values(#{name},#{pswd})</code>
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<code class="xml plain"></</code><code class="xml keyword">insert</code><code class="xml plain">></code>
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<strong>2、Mapper中的方法</strong></p>
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<code class="sql keyword">int</code> <code class="sql keyword">insert</code><code class="sql plain">(Person person);</code>
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注意在调用这个方法时，返回的int值并不是主键，而是插入的记录数。主键id会被赋值到输入的person对象里，自动赋值给person对象的id属性。比如：</p>
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<code class="java plain">Person person = </code><code class="java keyword">new</code> <code class="java plain">Person(</code><code class="java string">"name"</code><code class="java plain">,</code><code class="java string">"psw"</code><code class="java plain">);</code>
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<code class="java comments">//num是插入的记录数</code>
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<code class="java keyword">int</code> <code class="java plain">num = PersonMapper.insert(person);</code>
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<code class="java comments">//person对象的id属性会变成自生成的id</code>
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<code class="java keyword">int</code> <code class="java plain">id = person.getId();</code>
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