2012年最具影响力路由器配置精品文章荟萃【108篇】

"When you need a value from the first or last row of a sorted group, but the needed 

value is not the sort key, the FIRST and LAST functions eliminate the need for 

self-joins or views and enable better performance."

 

SELECT department_id,
MIN(salary) KEEP (DENSE_RANK FIRST ORDER BY commission_pct) "Worst",
MAX(salary) KEEP (DENSE_RANK LAST ORDER BY commission_pct) "Best"
FROM employees
GROUP BY department_id;

 

From Oracle Document