order by case when currency = 'USD' then 1 when currency = 'BHT' then 2 when currency = 'JPY' then 3 when currency = 'MYR' then 4 else 5 end. Re: Oracle Slow Order By Clause Solomon Yakobson 2012-5-4 下午12:52 （ 回复 811055 ） CengizU wrote: Query for second 100 row is: SELECT * FROM ( SELECT * FROM SFDC31E ORDER BY EVRAKNO ) WHERE ROWNUM>=101 AND ROWNUM<=200 ; This time query execution takes 138 seconds to complete. The Oracle database, by default, will not sort the results … SELECT DISTINCT TO_DATE(e.PUB_DATE_PRINT, 'DD Mon YYYY') AS "Publication Date" FROM TABLE ORDER BY 1 To sort the results set, we use the ORDER BY clause.
Ask Question Asked 7 years, 7 months ago. SELECT to_char( your_date_column, your_format_mask ) FROM your_table ORDER BY your_date_column. Now I have added one option in user settings where You would use ORDER BY and GROUP BY in the same query any time you wanted to guarantee the order of the rows returned. or a bit more compact but Oracle specific: order by decode(currency, 'USD', 1, 'BHT', 2, 'JPY', 3, 'MYR', 4, 5) The above solution using numbers to defined the sort order will not automatically sort currencies correctly that aren't mentioned in the case/decode … The above query sorts only the column 'salary' in descending order and the column 'name' by ascending order. Is this what you want? If you want to sort the data in descending order, you must explicitly specify it as shown below. Adding the rowid to the “order by” clause shouldn’t make any difference to the plan as the index Oracle is using is a single column non-unique index, which means that the internal representation makes it a two-column index where the rowid is (quite literally) stored as the second column. By default, the ORDER BY Clause sorts data in ascending order. When I am running a query as bellow with "order by 1" in a select statement on a dblink it's keep on processing in one instance (There are only 35 rows there) SELECT name d,ID r FROM namelist@dblinknew. In the SELECT list, you want to return a character string that represents the date in your preferred format. rgds, APC But here are the two execution plans: As Mscallion said, in earlier versions of Oracle, a GROUP BY was typically done using a sort, so the rows tended to come out sorted by the grouping columns, however this was not guaranteed.
Active 3 years, 3 months ago. To avoid the sort operation you can build an index as it maintains a sorted structure. Developers and DBAs get help from Oracle experts on: 'Order by' within or outside View, gives same execution plan and results select author_last_name from author order by author_last_name; The Oracle ORDER BY clause must be used if you require that the rows be sorted. order by 1; where as when I ran the query as bellow it worked perfectly instead of 'order by 1' I have used 'order by name' if you don't want it to appear in your output you can suppress it in SQL*Plus with this COL sort_order NOPRINT remember to include it in your group by. Sorting data is an expensive operation and many queries declare an ORDER BY. If you want it in DATE (ie calendrical order) then you will have to include a date column in your query eg to_date( to_char(date,'MON-YYYY'),'MON-YYYY') as sort_order. By Franck Pachot . Optimize Oracle order by query. However, indexes are sorted by binary values. Using the standard EMP and DEPT tables, for example. This helps with Top-N queries as you don’t have to read all rows but only those from a range of index entries.
In the ORDER BY clause, you want to order by the actual date. Order by is the last clause in the query to be applied, so it already has the final resultset to work on. Viewed 9k times 5. I am working on social media type application in which companies will upload posts from admin side and all the users can see the posts on user side.