MySQL ALTER statement usage

// Primary key

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

// Add a new column

 
Alter table T2 add D timestamp;
Alter table Infos add ex tinyint not null default '0 ';
 

// 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 bigint not null;
Alter table Infos change 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;