2修改数据库和表的字符集
alter database maildb default character set utf8;//修改数据库的字符集
alter table mailtable default character set utf8;//修改表的字符集
增加字段
ALTER TABLE wap_lenovo_bookmark ADD free BIT NOT NULL DEFAULT 0
alter table MemailNodeDefine add action varchar(50) CHARACTER SET utf8 COLLATE utf8_bin NOT NULL default 'admin';
给一个字段赋值
UPDATE "表格名" SET "栏位1" = [新值] WHERE {条件}
UPDATE wap_lenovo_bookmark set type = 'other'
ALTER TABLE wap_lenovo_bookmark ADD groupid INT NOT NULL DEFAULT 0
mysql 修改字段
alter table employee change column employeeID empID int;
修改
ALTER TABLE TableName CHANGE Field_name_tobe_change new_Name VARCHAR (32);
删除
ALTER TABLE TableName DROP Field_name_tobe_delete
重命名
ALTER TABLE TableName rename as newTableName
alter table 语句好像不能对表实行字段删除操作，可以用create table tablename(field1,field2,field3......) (select field1,field2,field3......from orgtablename);
或者用ALTER TABLE TableName DROP [COLUMN] col_name；
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mysql alter 语句用法,添加、修改、删除字段等
//主键549830479
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549830479
alter table t2 add d timestamp;
alter table infos add ex tinyint not null default '0';
//删除列549830479
alter table t2 drop column c;
//重命名列549830479
alter table t1 change a b integer;
//改变列的类型549830479
alter table t1 change b b bigint not null;
alter table infos change list list tinyint not null default '0';
//重命名表549830479
alter table t1 rename t2;
加索引549830479
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549830479
mysql> alter table tablename add primary key(id);
加唯一限制条件的索引549830479
mysql> alter table tablename add unique emp_name2(cardnumber);
删除某个索引549830479
mysql>alter table tablename drop index emp_name;
修改表：549830479
增加字段：549830479
mysql> ALTER TABLE table_name ADD field_name field_type;
修改原字段名称及类型：549830479
mysql> ALTER TABLE table_name CHANGE old_field_name new_field_name field_type;
删除字段：549830479
mysql> ALTER TABLE table_name DROP field_name;
