MariaDB - 更新後的複雜觸發查詢

Question

我有三個表（餐廳 - 票 - 評論）。我想創建一個觸發器，讓我更新餐館中的兩個字段（restaurant_rate_average，restaurant_comment_count）。這裏是我的觸發器：

DELIMITER $$ 

CREATE 
    TRIGGER `change comment status` AFTER UPDATE ON `comments` 
    FOR EACH ROW 
    BEGIN 

     UPDATE restaurants 
     INNER JOIN votes ON restaurants.restaurant_id = votes.vote_foreign_key 
     SET restaurants.restaurant_comment_count = SELECT (COUNT(votes.vote_id)) 
     WHERE votes.vote_model = 'restaurant' 
     AND WHERE old.comment_status<>NEW.comment_status; 

     UPDATE restaurants 
     INNER JOIN votes ON restaurants.restaurant_id = votes.vote_foreign_key 
     SET restaurants.restaurant_rate_average = SELECT (AVG(votes.vote_num)) 
     WHERE votes.vote_model = 'restaurant' 
     AND WHERE old.comment_status<>NEW.comment_status; 
    END; 
$$ 

DELIMITER ; 

其實我有一個錯誤：

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'SELECT (COUNT(votes.vote_id)) 
     WHERE votes.vote_model = 'restaurant' 
     ' at line 8 

我試圖讓膚色更小，並用2替換SELECT（COUNT（votes.vote_id）），我得到新錯誤：

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'WHERE comments.comment_status<>NEW.comment_status; 

     UPDATE resta' at line 9 

如何解決？

編輯：

這裏是我的僞表：

餐館： restaurant_id，restaurant_comment_count（INT），restaurant_rate_average（INT）

評論： COMMENT_ID，comment_status （布爾），comment_content（varchar），votes_vote_id（id）

票： vote_id，vote_foreign_key（ID），vote_model（VARCHAR）

EDITED 2：

我創造新的簡單的觸發器，它剛剛加入三個表和它的作品般的魅力：

BEGIN 
    UPDATE restaurants res 
    INNER JOIN votes v ON v.vote_foreign_key = res.restaurant_id AND v.vote_foreign_key = 'restaurant' 
    INNER JOIN comments cm ON cm.votes_vote_id = v.vote_id 
    SET res.restaurant_rate_average = 2 
    WHERE cm.comment_status = NEW.comment_status; 
END 

但是，如果我更換SET res.restaurant_rate_average = 2與SELECT AVG（v.vote_id）我得到了一個錯誤。我也最後觸發編輯於：

我在第4行得到一個錯誤我想要的是取代靜態數量與SELECT AVG(votes.vote_num)

Answer 1

DROP TRIGGER IF EXISTS `update_comment_status`;CREATE DEFINER=`root`@`localhost` TRIGGER `update_comment_status` AFTER UPDATE ON `comments` FOR EACH ROW BEGIN 
    DECLARE RESTAURANT_RATE_AVERAGE INTEGER; 
    DECLARE RESTAURANT_COMMENT_COUNT INTEGER; 
    SET RESTAURANT_RATE_AVERAGE := (SELECT AVG(votes.vote_num) FROM votes); 
    UPDATE restaurants res 
    INNER JOIN votes v ON v.vote_foreign_key = res.restaurant_id AND v.vote_foreign_key = 'restaurant' 
    INNER JOIN comments cm ON cm.votes_vote_id = v.vote_id 
    SET restaurant_rate_average = RESTAURANT_RATE_AVERAGE 
    WHERE cm.comment_status = NEW.comment_status; 

    SET RESTAURANT_COMMENT_COUNT := (SELECT COUNT(votes.vote_id) FROM votes); 
     UPDATE restaurants res 
    INNER JOIN votes v ON v.vote_foreign_key = res.restaurant_id AND v.vote_foreign_key = 'restaurant' 
    INNER JOIN comments cm ON cm.votes_vote_id = v.vote_id 
    SET restaurant_comment_count = RESTAURANT_COMMENT_COUNT 
    WHERE cm.comment_status = NEW.comment_status; 

END