如果postid不存在，MySQL将记录插入到一​​个表到另一个表

Question

Is there any way to write query in better way than this if I want to insert postid from posts table to star_ratings table if the postid is not exists in star_ratings table.

INSERT INTO star_ratings(post_id) 
SELECT postid FROM posts 
WHERE type in ('D', 'B') 
AND postid NOT IN (SELECT post_id FROM star_ratings) 
ORDER BY postid ASC

Answer 1

The following EXISTS query might perform slightly better than what you have:

INSERT INTO star_ratings (post_id)
SELECT p.postid
FROM posts p
WHERE
    p.type IN ('D', 'B') AND
    NOT EXSITS (SELECT 1 FROM star_ratings s WHERE p.post_id = s.post_id);

Answer 2

You can try using left join too

INSERT INTO star_ratings(post_id) 
SELECT postid FROM posts left join star_ratings on posts.postid=star_ratings.post_id 
WHERE type in ('D', 'B') and star_ratings.post_id is null