摘要：-- 删除库 drop database if exists db_name; -- 强制删除库 drop database if exists db_name cascade; -- 删除表 drop table if exists table_name; -- 清空表 truncate tabl 阅读全文

摘要：sql语句定义的顺序 (1) SELECT (2)DISTINCT<select_list> (3) FROM <left_table> (4) <join_type> JOIN <right_table> (5) ON <join_condition> (6) WHERE <where_condi 阅读全文