就是以12345分组的意思 group by 英[ɡru:p bai] 美[ɡrup baɪ][词典] [计][WIN] 分组依据;[例句]It can improve performance if columns involved in ORDER BY and GROUP BY are indexed.如果为ORDER BY和GROUP BY所涉及的列建立了索引，那么可以提高性能。希望我的回答能帮到你 ...