Does SQL Have a Default Sort Order?

Does SQL have a default sort order?

In SQL, developers often assume a default sort order exists, even if no ORDER BY clause is used. However, it would be a mistake to expect FIFO ordering based on insertion time without ORDER BY or an index.

Best Practice: Always use the ORDER BY clause

To ensure predictable and consistent results, the best practice is to always include the ORDER BY clause in your SQL query. This ensures that the data is sorted in a specific order, regardless of any underlying sorting mechanism in the database.

Experience of non-deterministic sorting

While it is uncommon to encounter data reordering in a database without making any changes to the table, it is not impossible. Database management systems (DBMS) may use various indexing and optimization techniques, which may result in unpredictable ordering in some cases.

Conclusion

There is no default sort order in SQL. Relying on assumed ordering without explicit ordering can lead to unexpected results. Always include the ORDER BY clause to define the desired sort order and maintain data integrity and consistency across different query executions.

The above is the detailed content of Does SQL Have a Default Sort Order?. For more information, please follow other related articles on the PHP Chinese website!