MySQL's ORDER BY and LIMIT can be mixed. ORDER BY is used to sort query results, while LIMIT is used to limit the number of rows in the returned result set.
The underlying principle is that when a query is executed, MySQL first sorts the results according to the ORDER BY clause. Then, MySQL uses the LIMIT clause to limit the number of rows in the returned result set. By combining ORDER BY with LIMIT , you can slice the sorted results and return only the specified number of rows.
The processing flow of MySQL is as follows:
- Execute the query and filter according to the WHERE clause to obtain the result set that meets the conditions.
- Sort the result set according to the column specified in the ORDER BY clause, and perform the sorting operation according to the specified collation.
- Applying the LIMIT clause selects the specified number of rows as the final result set.
Exact execution may vary depending on index usage, table size, and query optimizer decisions. MySQL will optimize queries as much as possible, such as using indexes to speed up sorting operations, to improve performance.
In short, by using both ORDER BY and LIMIT in the query, you can obtain a specific number of result rows according to the specified collation.