mybatis内置参数

mybatis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:参数会被封装为一个map; _parameter就是代表这个map

• _databaseId；如果配置了DatabaseIdProvider标签

  • _databaseId就是代表当前数据库的别名

配置DatabaseIdProvider标签

在配置文件中配置

    <databaseIdProvider type="DB_VENDOR">
        <property name="MySQL" value="mysql"/>
        <property name="Oracle" value="oracle"/>
    </databaseIdProvider>

   public List<Employee> getEmpsTestInnerParameter(Employee employee);

<!--    public List<Employee>  getEmpsTestInnerParameter(Employee employee);-->
<select id="getEmpsTestInnerParameter" resultType="com.atguigu.mybatis.bean.Employee">
<!--<bind name = "_lastName" value = "'%'+lastName+'%'"/>-->
<if test = "_databaseId=='mysql'">
    select * from tb1_employee
    <if test = "_parameter!=null">
        where last_name like #{_parameter.lastName}
    </if>
</if>
   <if test = "_databaseId == 'oracle'">
       select * from employees
       <if test = "_parameter!=null">
           where last_name like #{_parameter.lastName}
       </if>
       
   </if>

</select>

    @Test
    public void test04() throws IOException {
        SqlSessionFactory sqlSessionFactory = getSqlSessionFactory();

        SqlSession sqlSession = sqlSessionFactory.openSession();

        try
        {
            EmployeeMapperDynamicSQL mapper = sqlSession.getMapper(EmployeeMapperDynamicSQL.class);


            Employee employee = new Employee();

            employee.setLastName("%a%");

            List<Employee> emps = mapper.getEmpsTestInnerParameter(employee);

            for (Employee e : emps)
            {
                System.out.println(e);
            }

        }finally {

            sqlSession.close();

        }
    }