query:
	update | insert | update | insert | select | alter | transaction;

select:
	SELECT select_item FROM join WHERE where_cond_2 group_by;

group_by:
	| GROUP BY X . field_name;

select_item:
	X . field_name | value | COUNT( X . field_name ) | AVG( Y . field_name );

from: 
	table_name AS X | ( select ) AS X;

where_cond_2:
	X . field_name < value;

where_cond_1:
	field_name < value;

insert:
	INSERT INTO table_name ( field_name , field_name ) VALUES ( value , value ) ;

update:
	UPDATE table_name AS X
	SET field_name = value
	WHERE where_cond_2 LIMIT digit;

delete:
	DELETE FROM table_name WHERE where_cond_1 LIMIT digit;

join:
	table_name AS X LEFT JOIN table_name AS Y ON ( X . field_name = Y . field_name ) ;

transaction: start | end;

start: START TRANSACTION;

end: COMMIT | ROLLBACK;

value:
	tinyint_unsigned;

table_name:
	B | C | D | E ;

field_name:
	'pk' | 'int_key' | 'int_nokey' ;

alter:
	ALTER online TABLE table_name DROP KEY letter |
	ALTER online TABLE table_name ADD key_type letter ( field_name , field_name ) |
	ALTER online TABLE table_name ADD key_type letter ( field_name ) ;
;

online:
	| ;

key_type:
	KEY | UNIQUE | PRIMARY KEY ;