Mybatis动态拼接sql
需求：查询某张表时条件不确定，可能有一个，可能有多个，也可能没有条件
<!-- 动态sql -->
<select id="fingUserList" parameterType="com.hl.myabtis.first.beas.UserQueryVo" resultType="com.hl.myabtis.first.beas.UserCustomer">
select * from user
<!-- where可以自动去掉条件中的第一个and -->
<where>
<if test="userCustomer!=null">
<if test="userCustomer.sex!=null and userCustomer.sex!=''">
and user.sex=#{userCustomer.sex}
</if>
<if test="userCustomer.address!=null and userCustomer.address!=''">
and user.address like '$%{userCustomer.address}%'
</if>
</if>
</where>
mapper接口：
public List<UserCustomer> fingUserList(UserQueryVo userQueryVo) throws Exception;
测试：
@Test
public void findUserCount() throws Exception{
SqlSession sqlSession = sqlSessionFactory.openSession();
UserMapper usermapper = sqlSession.getMapper(UserMapper.class);
//构建一个包装类
UserQueryVo userQueryVo = new UserQueryVo();
//构建一个增强类
UserCustomer userCustomer = new UserCustomer();
userCustomer.setAddress("明月");
userCustomer.setSex('1');
//包装类包装这增强类作为查询条件
userQueryVo.setUserCustomer(userCustomer);
//不加任何条件
int result = usermapper.findUserCount(null);
System.out.println(result);
sqlSession.close();
}