在MySQL中有效处理不同类型的"follow“函数

CREATE PROCEDURE follow_user(IN follower_id INT, IN following_id INT)
BEGIN
    -- 检查是否已经存在关注关系
    IF EXISTS(SELECT * FROM follow_table WHERE follower_id = follower_id AND following_id = following_id) THEN
        -- 取消关注
        DELETE FROM follow_table WHERE follower_id = follower_id AND following_id = following_id;
    ELSE
        -- 关注用户
        INSERT INTO follow_table (follower_id, following_id) VALUES (follower_id, following_id);
    END IF;
END;

CREATE TRIGGER after_follow
AFTER INSERT ON follow_table
FOR EACH ROW
BEGIN
    -- 更新用户的关注数和被关注数
    UPDATE user_table SET following_count = following_count + 1 WHERE user_id = NEW.follower_id;
    UPDATE user_table SET followers_count = followers_count + 1 WHERE user_id = NEW.following_id;
END;