CREATE TABLE category (
  id smallint( 5 ) unsigned NOT NULL default '0',
  name tinytext NOT NULL
) TYPE=MyISAM COMMENT='Категории каталога';

CREATE TABLE property (
  id smallint( 5 ) unsigned NOT NULL auto_increment,
  name varchar( 255 ) binary NOT NULL default '',
  PRIMARY KEY  (id)
) TYPE=MyISAM COMMENT='Характеристики' AUTO_INCREMENT= 16  ;

CREATE TABLE tovar (
  id int( 10 ) unsigned NOT NULL auto_increment,
  name varchar( 255 ) binary NOT NULL default '',
  category_id smallint( 5 ) unsigned NOT NULL default '0',
  PRIMARY KEY  (id),
  KEY category_id (category_id)
) TYPE=MyISAM COMMENT='Товары';

CREATE TABLE value (
  tovar_id int( 10 ) unsigned NOT NULL default '0',
  property_id smallint( 5 ) unsigned NOT NULL default '0',
  value tinytext NOT NULL,
  PRIMARY KEY  (tovar_id,property_id),
  KEY value (value( 10 ),property_id)
) TYPE=MyISAM COMMENT='Значения характеристик товаров';

SELECT
  tovar.id
FROM
  tovar,
  value value1,
  value value2,
  value value3
WHERE
  tovar.category_id =  1 
  AND value1.tovar_id = tovar.id
  AND value1.property_id = '5'
  AND value1.value = 'p_5353'
  AND value2.tovar_id = tovar.id
  AND value2.property_id = '10'
  AND value2.value = 'p_4128'
  AND value3.tovar_id = tovar.id
  AND value3.property_id = '12'
  AND value3.value = 'p_503'