数据库Mysql中alert用法详解_其他_php教程

/主键

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

//增加一个新列

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alter table t2 add d timestamp;

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

//删除列

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alter table t2 drop column c;

//重命名列

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alter table t1 change a b integer;

//改变列的类型

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alter table t1 change b b bigint not null;

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

//重命名表

alter table t1 rename t2;

加索引

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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);

加主关键字的索引

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

加唯一限制条件的索引

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

删除某个索引

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mysql>alter table tablename drop index emp_name;

修改表：

增加字段：

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mysql> ALTER TABLE table_name ADD field_name field_type;

修改原字段名称及类型：

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mysql> ALTER TABLE table_name CHANGE old_field_name new_field_name field_type;

删除字段：

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mysql> ALTER TABLE table_name DROP field_name;

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