深入理解MyBatis中的动态SQL语句(3)

<update parameterType="Student">
update students
<set>
<if test="name != null">name=#{name},</if>
<if test="email != null">email=#{email},</if>
<if test="phone != null">phone=#{phone},</if>
</set>
where stud_id=#{studId}
</update>

这里，如果<if>条件返回了任何文本内容，<set>将会插入set关键字和其文本内容，并且会剔除将末尾的逗号","。

测试方法：

@Test
public void test_updateStudent(){

SqlSession sqlSession = null;
try {
sqlSession = MyBatisSqlSessionFactory.openSession();

DynamicSqlMapper mapper = sqlSession.getMapper(DynamicSqlMapper.class);

Student student = new Student();
student.setStudId(45);
student.setEmail("xx@linuxidc.com");

mapper.updateStudent(student);

sqlSession.commit();

} catch (Exception e) {
e.printStackTrace();
}
}

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