mysql alter语句用法实例
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2024-02-21 09:03:16
//主键 alter table tablename add new_field_id int(5) unsigned default 0 not null anto_in...
//主键
alter table tablename add new_field_id int(5) unsigned default 0 not null anto_increment,add primary key (new_field_id);
//增加一个新列
mysql>alter table tablename add fieldname fieldtype
如:
alter table t2 add d timestamp;
alter table infos add ex tinyint not null default '0';
//删除列
mysql>alter table table_name drop field_name
如:
alter table t2 drop column c;
//修改原字段名称及类型
mysql>alter table tablename change old_field_name new_field_name field_type;
如:
//重命名列
alter table t1 change a b integer;
//改变列的类型
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
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);
//加主关键字的搜索
mysql>alter table tablename add primary key(id);
//加唯一限制条件的索引
mysql>alter table tablename add unique emp_name2(cardnumber);
//删除某个索引
mysql>alter table tablename drop index emp_name;
alter table tablename add new_field_id int(5) unsigned default 0 not null anto_increment,add primary key (new_field_id);
//增加一个新列
mysql>alter table tablename add fieldname fieldtype
如:
alter table t2 add d timestamp;
alter table infos add ex tinyint not null default '0';
//删除列
mysql>alter table table_name drop field_name
如:
alter table t2 drop column c;
//修改原字段名称及类型
mysql>alter table tablename change old_field_name new_field_name field_type;
如:
//重命名列
alter table t1 change a b integer;
//改变列的类型
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
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);
//加主关键字的搜索
mysql>alter table tablename add primary key(id);
//加唯一限制条件的索引
mysql>alter table tablename add unique emp_name2(cardnumber);
//删除某个索引
mysql>alter table tablename drop index emp_name;