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//Ö÷¼ü
alter table tabelname add new_field_id int(5) unsigned default 0 not null auto_increment ,add primary key (new_field_id);
//Ôö¼ÓÒ»¸öÐÂÁÐ
alter table t2 add d timestamp;
alter table infos add ex tinyint not null default '0';
//ɾ³ýÁÐ
alter table t2 drop column c;
//ÖØÃüÃûÁÐ
alter table t1 change a b integer;
//¸Ä±äÁеÄÀàÐÍ
alter table t1 change b b bigint not null;
alter table infos change list list tinyint not null default '0';
//ÖØÃüÃû±í
alter table t1 rename t2;
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mysql> alter table tablename change depno depno int(5) not null;
mysql> alter table tablename add index Ë÷ÒýÃû (×Ö¶ÎÃû1[£¬×Ö¶ÎÃû2 …]);
mysql> alter table tablename add index emp_name (name);
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mysql> alter table tablename add primary key(id);
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mysql> alter table tablename add unique emp_name2(cardnumber);
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mysql>alter table tablename drop index emp_name;
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mysql> ALTER TABLE table_name ADD field_name field_type;
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mysql> ALTER TABLE table_name CHANGE old_field_name new_field_name field_type;
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mysql> ALTER TABLE table_name DROP field_name;


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  Æô¶¯£ºnet start mySql;
  ½øÈ룺mysql -u root -p/mysql -h localhost -u root -p databaseName;
  ÁгöÊý¾Ý¿â£ºshow databases;
  Ñ¡ÔñÊý¾Ý¿â£ºuse databaseName;
  Áгö±í¸ñ£ºshow tables£»
  ÏÔʾ±í¸ñÁеÄÊôÐÔ£ºshow columns from tableName£»
  ½¨Á¢Êý¾Ý¿â£ºsource fileNa ......

.\mysql\user is marked as crashed ½â¾ö°ì·¨

 
I found a solution to anyone else who may be having this problem.
First start mysql using skip grant tables
root@ns1 [/var/lib/mysql/mysql]# service mysql start --skip-grant-tables
Starting MySQL [ OK ]
now with mysql started, you can repair the mysql/user table
root@ns1 [/var/lib/mysql ......

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mysql -u root -pvmwaremysql>use mysql;mysql>update use ......

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[condition] THEN result [WHEN[condition] THEN result …… ......
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