1. Add a field:
ALTER TABLE tablename add NEW_FIELD_ID type NOT null default ' 0 ';
Cases:
ALTER TABLE Mmanapp_mmanmedia add appid_id integer NOT null default 372;
Add primary key:
alter table tabelname add new_field_id type default 0 not nullauto_increment,add primary key (new_field_id);
add foreign key:
Add a FOREIGN KEY constraint on a field that already exists
ALTER TABLE yourtablename ADD [CONSTRAINT symbol] FOREIGN KEY [id] (index_col_name, ...) REFERENCES tbl_name (index_col_name, ...) [on DELETE {RESTRICT | CASCADE | SET NULL | NO ACTION}] [on UPDATE {RESTRICT | CASCADE | SET NULL | NO ACTION}]
2. Delete a field:
ALTER TABLE tablename drop column colname;
Cases:
ALTER TABLE mmanapp_mmanmedia drop column appid_id;
3. Modify the field name:
ALTER TABLE tablename change Old_field_name new_field_name old_type;
4. Modify the field type:
ALTER TABLE tablename change Filed_name filed_name new_type;