Back
Syntax
Study
Editor
Mode:
HTML
CSS
JavaScript
PHP
Reset
Run »
HTML / CSS / JS
-- Normalized: count comments by querying comments table (slow) SELECT COUNT(*) FROM comments WHERE post_id = 1; -- Denormalized: store comment_count on posts table ALTER TABLE posts ADD COLUMN comment_count INT DEFAULT 0; -- Update on insert UPDATE posts SET comment_count = comment_count + 1 WHERE id = ?;
Result
Open