Here is nice gotcha which I've seen many times and which can
cause just a minefield for many reasons.
Lets say you had a system storing articles and you use article_id as unsigned int. As the time goes and you see you may get over 4 billions of articles you change the type for article_id to bigint unsigned but forget linked tables.
PLAIN TEXT SQL:
- mysql> CREATE TABLE article_comment(article_id int UNSIGNED NOT NULL, comment_id int UNSIGNED NOT NULL, …