An ORDER BY clause sorts the rows returned by an SQL query. For example, a movie application can show the highest-rated movies first by sorting rating values in descending order. section 7.9
Show the 30 highest-rated movies
SELECT * FROM movie ORDER BY rating DESC LIMIT 30; The database reads movie rows, selects the columns, sorts them by rating from highest to lowest, and then keeps the first 30 rows. DESC means descending order. section 7.9
Keep these practical rules in mind:
- Place ORDER BY after the rows and columns have been selected; LIMIT can then restrict the sorted result. section 7.9
- Sorting millions of rows repeatedly can slow an application, so an index on the sorted column may improve performance. section 7.9
-- comment: works for MySQL, MariaDB, -- comment: PostgreSQL and SQLite -- comment: consult ChatGPT on adaptations -- comment: for other RDBMS SELECT * FROM movie ORDER BY rating DESC LIMIT 30;
Run the complete movie query to see descending sorting combined with a 30-row limit. section 7.9
