数据库表结构常用操作
创建表:create table tablename( id int not null , name varchar(20), primary key(id,name));创建索引:create index indexname on tablename(columnname1,columnname2);删除索引:drop index indexname;删除表:drop table tablename;修改表结构:alter table tablename add( name1 varchar(20), default("1"), name2 varchar(20), not null)alter table tablename drop column columnnamealter table tablename modify name1 varchar(30);重命名一列:alter table tablename rename column columnname1 to columnname2放弃主键:alter table FAVOURITEINFO05 drop primary key;