MyBatis_[tp_48]_动态sql_内置参数_parameter&

笔记要点-----内置参数_parameter&_databaseId 用处: 迅速切换数据库,执行一条多分支的sql语句即可;
1.定义接口

public interface EmployeeMapper_DynamicSQL {

    public List<Employee> getEmpsTestInnerParameter(Employee employee);//测试内部参数

}

2.定义XML映射文件

    <!--两个内置参数;不只是方法传递过来的参数可以用来判断,取值

        mubatis默认还有两个内置参数:

        _parameter : 代表整个参数;

            单个参数: _parameter就是这个参数

            多个参数: 会被封装成一个map,map就是_parameter

        _databaseId : 如果配置了databaseIdProvider标签;

            _databaseId就是代表了当前数据库的别名mysql !

        -->

    <!--public List<Employee> getEmpsTestInnerParameter(Employee employee);//测试内部参数-->

    <select id="getEmpsTestInnerParameter" resultType="com.bean.Employee">

        <if test="_databaseId=='mysql'">

            select * from tbl_employee

            <if test="_parameter!=null">

                where last_name = #{_parameter.lastName}

            </if>

        </if>

        <if test="_databaseId=='oracle'">

            select * from tbl_employee

        </if>

3.编写测试代码

public class test_tp48 {

    public SqlSessionFactory getSqlSessionFactory() throws IOException {

        String resource = "mybatis-config.xml";

        InputStream inputStream = Resources.getResourceAsStream(resource);

        return new SqlSessionFactoryBuilder().build(inputStream);

    }

    @Test

    public void test11() throws Exception {

        SqlSession openSession = getSqlSessionFactory().openSession();

        try {

            System.out.println("++++++++++---- tp48.测试动态sql_内置参数_parameter&_databaseId");

            EmployeeMapper_DynamicSQL mapper = openSession.getMapper(EmployeeMapper_DynamicSQL.class);

            List<Employee> list = mapper.getEmpsTestInnerParameter(null);

            for(Employee e:list)

                System.out.println(e);

            openSession.commit();

        } finally {

            openSession.close();

        }

    }

}

测试结果

++++++++++---- tp48.测试动态sql_内置参数_parameter&_databaseId

DEBUG 12-05 17:45:17,805 ==>  Preparing: select * from tbl_employee   (BaseJdbcLogger.java:145)

DEBUG 12-05 17:45:17,828 ==> Parameters:   (BaseJdbcLogger.java:145)

DEBUG 12-05 17:45:17,845 <==      Total: 8  (BaseJdbcLogger.java:145)

Employee{id=1, lastName='Jerry2333', email='233@...', gender='1', dept=null}

Employee{id=4, lastName='葫芦娃', email='葫芦娃@163.com', gender='0', dept=null}

Employee{id=5, lastName='葫芦娃e', email='qwq@qq.com', gender='1', dept=null}

Employee{id=6, lastName='null', email='xxx@qq.com', gender='1', dept=null}

Employee{id=7, lastName='tom', email='tom@163.com', gender='0', dept=null}

Employee{id=8, lastName='frak', email='frak@163.com', gender='1', dept=null}

Employee{id=9, lastName='smith', email='smith@qq.com', gender='1', dept=null}

Employee{id=10, lastName='aliex', email='aliex@qq.com', gender='0', dept=null}

巴特西

MyBatis_[tp_48]_动态sql_内置参数_parameter&_databaseId

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