SQL(ORACLE):ORDER BY和LIMIT [英] SQL (ORACLE): ORDER BY and LIMIT

问题描述

我想按属性对数据库中的所有数据进行排序，并且仅在使用LIMIT和OFFSET之后.

I want do sorting by property ALL data in my db and ONLY AFTER that use LIMIT and OFFSET.

这样查询:

SELECT select_list
    FROM table_expression
    [ ORDER BY ... ]
    [ LIMIT { number | ALL } ] [ OFFSET number ] 

我知道排序一旦找到排序结果的头row_count行，排序就会结束.我可以在调用LIMIT和OFFSET之前对所有数据进行排序吗?

I know the sorting ends as soon as it has found the first row_count rows of the sorted result. Can I do sorting all data before calling LIMIT and OFFSET?

推荐答案

在12.1之前，Oracle不支持LIMIT或OFFSET关键字.如果要检索结果集的第N到M行，则需要类似以下内容的

Prior to 12.1, Oracle does not support the LIMIT or OFFSET keywords. If you want to retrieve rows N through M of a result set, you'd need something like:

SELECT a.*
  FROM (SELECT b.*,
               rownum b_rownum
          FROM (SELECT c.*
                  FROM some_table c
                 ORDER BY some_column) b
         WHERE rownum <= <<upper limit>>) a
 WHERE b_rownum >= <<lower limit>>

或使用解析功能:

SELECT a.*
  FROM (SELECT b.*,
               rank() over (order by some_column) rnk
          FROM some_table)
 WHERE rnk BETWEEN <<lower limit>> AND <<upper limit>>
 ORDER BY some_column

这两种方法都会对排序结果的N到M行进行排序.

Either of these approaches will sort give you rows N through M of the sorted result.

在12.1和更高版本中，可以使用OFFSET和/或FETCH [FIRST | NEXT]运算符:

In 12.1 and later, you can use the OFFSET and/or FETCH [FIRST | NEXT] operators:

SELECT *
  FROM some_table
 ORDER BY some_column
 OFFSET <<lower limit>> ROWS
  FETCH NEXT <<page size>> ROWS ONLY

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