show databases;//然后可以use database_name;
show tables;

alter table table_name rename new_t;

alter table table_name add column c_n column attributes;

alter table table_name drop column c_n;

alter table c_table add index (c_n1,c_n2);
alter table c_table add unique index_name(c_n);
alter table c_table add primary key(sid);

alter table c_table drop index c_n1;

alter table t_table change c_1 c_1 varchar(200);
alter table t_table modify 1 c_1 varchar(200);

insert into table_name (c_1,c_2)
values ('x1′,1);

update table_name set c_1 =1 where c_2=3;

drop table table_name;
drop database database_name;//使用mysql_drop_db()可以删除的.