Gbase8s database select has order by Clause 6

You may exclude CONNECT BY Clauses SELECT The final of the clause ORDER BY Clause includes OLAP

window function .

If in ORDER BY Clause OLAP Function clause , It's in ORDER BY Before evaluation , Evaluate first OLAP Letter

Count .

Generally speaking , For including one or more OLAP window The function is simple SELECT sentence , The database server follows

The following processing order ：

Connect any connection 、 filter 、GROUP BY or HAVING The specification is applied to get a collection of qualified rows , Come on

Return as a query set .

To create a matching row window Partition , And will designate OLAP Function is applied to each partitioned result set （ or

Apply to this query result set , If no partition is defined ） Each line in .

take SELECT Of the statement ORDER BY Clause is applied to the final query result .

For nested queries , Each subquery follows the above order , But will OLAP window Partition and its OLAP The function applies to the most

The result set of the subquery , Define the... In it OLAP window.

If OLAP window Include window ORDER Clause , Then that clause , instead of SELECT Of the statement ORDER

BY Clause , Definition window ROW_NUMBER Functions in the same OLAP window The rows assigned to these rows in the partition of

Number . However ,window ORDER Clause does not define the sort of the query result set , from SELECT Of the statement ORDER BY Son

Sentence definition .

If OLAP window barring window ORDER Clause , In any order window ROW_NUMBER

The function assigns the row number to these rows , As returned by a query or subquery , Not based on SELECT Any of the statements

ORDER BY Clause .