基于左右值的树形结构的数据库表Schema设计

参考：https://blog.csdn.net/MONKEY_D_MENG/article/details/6647488
https://blog.csdn.net/dreajay/article/details/8894058
https://www.cnblogs.com/cbryge/p/6015347.html
https://blog.csdn.net/tiantiandjava/article/details/45390859
https://www.cnblogs.com/dataadapter/archive/2012/08/29/2661600.html
https://blog.csdn.net/lj1314ailj/article/details/52074216
https://blog.csdn.net/zhaoxuejie/article/details/52623134