Oracle 23c New Features for DBA'sDo you want to restrict row results not to display/retrieve fully?
Until 11g, Oracle uses Top -n query method to retrieve top or bottom set of data using rownum, dense, rank etc.
But this has limitation when order is required for that data and also an inline view is required and complex to write.
For example for simple query that need to return top 5 rows:-
SELECT sal FROM (SELECT sal FROM employees ORDER BY sal) WHERE rownum < = 5;
To do the same in 12c,
SELECT sal FROM employees ORDER BY sal DESC FETCH FIRST 5 ROWS ONLY;
The later one is just simple and easy to understand as well.
In addition to fetch above, there are an options like Ties, Percentage of data to return, specific set of data when grouping
Read more here:-
http://docs.oracle.com/cd/E16655_01/server.121/e17209/statements_10002.htm#BABHFGAA
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