学步园

select a,b,count(sum(c)) over ()            
from test                                     
where t.d=1                                 
start with e is not null connect by prior f=g
group by a,b                                
having sum(c)>100                           
order by a;                                 
                                            
这个SQL包含：                               
1. SELECT 子句                              
2. group by子句                             
3. 分析函数                                 
4. from子句                                 
5. where子句                                
6. start with...connect by子句              
7. having子句                               
8. order by子句                             
                                            
4 -> 6 -> 5 -> 2 -> 7 -> 3 -> 8 -> 1

最后是的顺序是8到1还是1到8不用纠结这里的select可以理解为在操作的时候，先给各列赋予别名与序号，
然后order by进行排序，排序结果，再通select展现出来。