Shulou(Shulou.com)06/01 Report--

The sorting algorithm is divided into stable sorting and unstable sorting. In general, unstable sorting has a lower time complexity.

In oracle, you should also note that the sorted result set may not be the target result set.

1, no collation specified

Select * from t order by something

The default growing sort (ASCENDING) is used

2. Permutation is not the only key or there is repetition in the combination of permutation.

At this time, the data of the top 10 items obtained by querying 10 items and 11 items may be inconsistent.

3, no sort sequence specified

Select * from t

Very common way of writing, at this time the data does not have any sort (in Ask Tom Tom answers Unless and until you add "order by" to a query, you cannot say ANYTHING about the order of the rows returned. The original address), so in a paging query, the data in the first page may appear on the third page.

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