New MySQL field addition field deletion field modification field cascading deletion cascade update and so on

// Primary key

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

// Delete a column

alter table t2 drop column c;

// Rename a column

alter table t1 change a b integer;

// Change the column type

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

// Rename the table

alter table t1 rename t2;

Add Index

Mysql> alter table tablename change depno int (5) not null; mysql> alter table tablename add Index name (field name 1 [, field name 2…]); Mysql> alter table tablename add index emp_name (name );

Index with primary keywords

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

Add an index with unique conditions

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

Delete An index

mysql>alter table tablename drop index emp_name;

Modify Table:

Add field:

mysql> ALTER TABLE table_name ADD field_name field_type;

Modify the original field name and type:

mysql> ALTER TABLE table_name CHANGE old_field_name new_field_name field_type;

Delete field:

mysql> ALTER TABLE table_name DROP field_name;

Cascade update and delete (red, Case Insensitive)

DROP TABLE IF EXISTS `mail_model`;
create table mail_model(
id varchar(50) primary key not null ,
mail_filename varchar(200),

content varchar(2000)
)ENGINE=InnoDB DEFAULT CHARSET=gbk;

DROP TABLE IF EXISTS `mail_model_extend`;
create table mail_model_extend(
id int(6) auto_increment not null primary key,
rid varchar(50) not null,
content varchar(2000),
INDEX (RID),
FOREIGN KEY (RID) REFERENCES mail_model(ID) ON DELETE CASCADE ON UPDATE CASCADE
)ENGINE=InnoDB DEFAULT CHARSET=gbk;