用另一个COUNT表更新一个MySQL表

Question

I'm trying to update a column in table Profiles with a COUNT from another table Videos . All videos are stored in the Videos table, and I want to create a column in Profiles called VideoCount which shows the COUNT of that user's videos in the Videos table.

Basically, I want to run a cron job - so I need to know how to find the COUNT of a user's videos in the Videos table and then UPDATE that user's VideoCount in Profiles with this count number.

To identify who's uploaded which video, Videos . Owner and Profiles . ID should be made to match. Does anybody know the SQL which I need to run for the PHP file cron job?

Answer 1

UPDATE Profiles
SET VideoCount = (
   SELECT COUNT(*)
   FROM Videos
   WHERE Videos.Owner = Profiles.ID);

as simple as it can be^^

and if you want it fancy: all the triggers you might need:

DELIMITER //

CREATE TRIGGER increaseVideoCount AFTER INSERT ON Videos
  FOR EACH ROW BEGIN
    UPDATE Profiles SET VideoCount = VideoCount + 1 WHERE ID = NEW.Owner;
  END;
//

CREATE TRIGGER decreaseVideoCount AFTER DELETE ON Videos
  FOR EACH ROW BEGIN
    UPDATE Profiles SET VideoCount = VideoCount - 1 WHERE ID = OLD.Owner;
  END;
//

CREATE TRIGGER checkVideoCount AFTER UPDATE ON Videos
  FOR EACH ROW BEGIN
    IF OLD.Owner <> NEW.Owner THEN
      UPDATE Profiles SET VideoCount = VideoCount + 1 WHERE ID = NEW.Owner;
      UPDATE Profiles SET VideoCount = VideoCount - 1 WHERE ID = OLD.Owner;
    END IF;
  END;
//

DELIMITER ;

Answer 2

If you want to update video count that you can upadate video count at the time of upload, so as i think there is no need for the cron job for this.

update profiles set videocount=(select count(*) from videos where profileid =$profileid ) 
where profileid=$profileid

Answer 3

Something like

UPDATE A SET VideoCount = 
(
  SELECT COUNT(B.*) 
  FROM Videos AS B INNER JOIN Profiles AS B ON (A.Profile_ID = B.Owner_ID)  
  GROUP BY B.Owner_ID
);

I'm not sure this syntax is completely correct. give it a try