SQL (ORACLE): ORDER BY and LIMIT [duplicate]
I want do sorting by property ALL data in my db and ONLY AFTER that use LIMIT and OFFSET.
Query like this:
SELECT select_list
FROM table_expression
[ ORDER BY ... ]
[ LIMIT { number | ALL } ] [ OFFSET number ]
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?
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>>
or using analytic functions:
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
Either of these approaches will sort give you rows N through M of the sorted result.
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