标签：row 选项 order avg nbsp rom win esc run
1.qualify
是一个潜在的额外筛选器
主要用于对开窗函数的数据筛选
SELECT orderid, orderdate, val, RANK() OVER(ORDER BY val DESC) AS rnk FROM Sales.OrderValues QUALIFY rnk <= 5;
标准SQL没用定义qualify子句，它是Teredata特有的特性。
2.window
允许我们对窗口进行命名描述；然后在定义其他窗口-即将被串钩函数使用或用来定义另一个命名窗口时，代指这个命名的窗口描述。
如下
SELECT empid, ordermonth, qty, SUM(qty) OVER (PARTITION BY empid ORDER BY ordermonth ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS run_sum_qty, AVG(qty) OVER (PARTITION BY empid ORDER BY ordermonth ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS run_avg_qty, MIN(qty) OVER (PARTITION BY empid ORDER BY ordermonth ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS run_min_qty, MAX(qty) OVER (PARTITION BY empid ORDER BY ordermonth ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS run_max_qty FROM EmpOrders;
用window缩写前置查询
SELECT empid, ordermonth, qty, SUM(qty) OVER W1 AS run_sum_qty, AVG(qty) OVER W1 AS run_avg_qty, MIN(qty) OVER W1 AS run_min_qty, MAX(qty) OVER W1 AS run_max_qty FROM Sales.EmpOrders WINDOW W1 AS ( PARTITION BY empid ORDER BY ordermonth ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW );
window吧一个带有分区，排序和框架选项的完整的窗口描述为w1
标签：row 选项 order avg nbsp rom win esc run
原文地址：https://www.cnblogs.com/yuanzijian-ruiec/p/10127532.html
