```
If multiple rows have identical values in the ORDER BY columns, the server is free to return those rows in any order, and may do so differently depending on the overall execution plan. In other words, the sort order of those rows is nondeterministic with respect to the nonordered columns.
One factor that affects the execution plan is LIMIT, so an ORDER BY query with and without LIMIT may return rows in different orders. Consider this query, which is sorted by the category column but nondeterministic with respect to the id and rating columns:
```
来自
https://dev.mysql.com/doc/refman/8.0/en/limit-optimization.html简单来说 :如果在 ORDER BY 列中有多个行具有相同的值,则服务器可以自由以任何顺序返回这些行,并且根据整体执行计划的不同,返回值可能会有所不同。