Prestashop multishop

1) make soft link of image folder from main shop to new shop

ln -fs main_shop/img new_shop/img

2)Rename new_shop_db and main_shop_db to your names in sql procedure and run sql script

DELIMITER $$
DROP PROCEDURE if exists make_linked_tables $$

CREATE PROCEDURE make_linked_tables() 
BEGIN
DECLARE done INT DEFAULT FALSE;
DECLARE str VARCHAR(250);
DECLARE cur CURSOR FOR 
 SELECT table_name FROM information_schema.tables WHERE 
table_schema = 'new_shop_db' AND (table_name LIKE 'ps_product%'
OR  table_name LIKE 'ps_category%') 
UNION
SELECT 'ps_image'
UNION
SELECT 'ps_image_lang'
;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
OPEN cur;
REPEAT
 FETCH cur INTO str;
 SET @s = CONCAT("RENAME TABLE ", str," TO ");
 SET @s = CONCAT(@s,str,"_orig");
 PREPARE sth FROM @s;
 EXECUTE sth;
 DEALLOCATE PREPARE sth;

 SET @s = CONCAT("CREATE VIEW ",str," as SELECT * FROM main_shop_db.",str);
 PREPARE sth2 FROM @s;
 EXECUTE sth2;
 DEALLOCATE PREPARE sth2;

UNTIL done END REPEAT;
CLOSE cur;
END$$
DELIMITER ;

3)Run procedure

CALL make_linked_tables();
DROP PROCEDURE if exists make_linked_tables; 

Manually customize categories list of new shop:

drop table if exists ps_category;
create OR replace view ps_category AS
SELECT * FROM MAIN_SHOP_DB.`ps_category` WHERE 
id_category in ( 1,17,28,35) OR id_parent in (17,28,35);

drop table if exists ps_category_group;
create OR replace view ps_category_group AS
SELECT * FROM MAIN_SHOP_DB.`ps_category_group` WHERE 
id_category in ( SELECT id_category FROM `ps_category` ) ;

drop table if exists ps_category_lang;
create OR replace view ps_category_lang AS
SELECT * FROM MAIN_SHOP_DB.`ps_category_lang` WHERE 
id_category in ( SELECT id_category FROM `ps_category`);

drop table if exists ps_category_product;
create OR replace view ps_category_product AS
SELECT * FROM MAIN_SHOP_DB.`ps_category_product` WHERE 
id_category in ( SELECT id_category FROM `ps_category`) ;

There are  id_category = 1 - main category(required), 17(subcategory optional)  ....