mysql alter

alter table tabelname add new_field_id int(5) unsigned default 0 not null auto_increment ,add primary key (new_field_id);

alter table t2 add d timestamp;
alter table infos add ex tinyint not null default '0';

alter table t2 drop column c;

alter table t1 change a b integer;

alter table t1 change b b bigint not null;
alter table infos change list list tinyint not null default '0';

alter table t1 rename t2;

mysql> alter table tablename change depno depno int(5) not null;
mysql> alter table tablename add index 索引名 (字段名1[，字段名2 …]);
mysql> alter table tablename add index emp_name (name);

mysql> alter table tablename add primary key(id);

mysql> alter table tablename add unique emp_name2(cardnumber);

mysql>alter table tablename drop index emp_name;

mysql> ALTER TABLE table_name ADD field_name field_type;

mysql> ALTER TABLE table_name CHANGE old_field_name new_field_name field_type;

mysql> ALTER TABLE table_name DROP field_name;

picked from :http://www.blogjava.net/alpha/archive/2007/07/23/131912.html

删除外键：
ALTER TABLE articles DROP FOREIGN KEY articles_ibfk_1;

但是如果定义时没有指定CONSTRAINT fk_symbol （即外键符号）时该怎么实现MySQL删除外键呢？别急，没有指定时，MySQL默认会自己创建一个，可以通过以下命令查看：
　　SHOW CREATE TABLE articles;
然后再执行上面的命令删除。

修改表字符集：
ALTER TABLE tbl_name CONVERT TO CHARACTER SET charset_name;