数据库开发与实例（1+1混合数据库开发实例丛书）人事管理系统的源代码-Database development and examples of (1+1 example of a mixed database development series) personnel management system source code

Renewable energy can be defined initially as any energy source that is derived directly or indirectly solar energy. In the broadest sense, however, almost all of the energy we use today, including fossil fuels, can be considered a form of solar