摘要： 登录mysql –u username –p password，查看数据库show databases，切换数据库use databasename，查看表show tables，查看表结构describe tablename或show columns from tablename，创建表语句show create table tablename。 时间处理：存为字符串的long型时间通常是15个... 阅读全文

摘要： 1. 查询：select column from table where condition group by column having condition order by column limit start,end a) 去掉重复：select disdinct column from table b) 条件：select column from table where condition... 阅读全文