Here are some usage of mysqlalter statements for your convenience.
Here are some simple usage of mysql alter statements for your convenience.
// Primary key
Alter table tablename add new_field_id int (5) unsigned default 0 not null anto_increment, add primary key (new_field_id );
// Add a new column
Mysql> alter table tablename ADD fieldname fieldtype
For example:
Alter table t2 ADD d TIMESTAMP;
Alter table infos ADD ex tinyint not null default '0 ';
// Delete a column
Mysql> alter table table_name DROP field_name
For example:
Alter table t2 drop column c;
// Modify the original field name and type
Mysql> alter table tablename CHANGE old_field_name new_field_name field_type;
For example:
// 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 an 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 );
// Search with the primary keyword
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;
