转载:https://blog.csdn.net/u014044812/article/details/51004754
大致:from > join > on > group by > avg/sum > having > select > order by > limit
转载:https://blog.csdn.net/u014044812/article/details/51004754
大致:from > join > on > group by > avg/sum > having > select > order by > limit