1.qualify

是一個潛在的額外篩選器

主要用於對開窗函式的資料篩選

SELECT orderid, orderdate, val,
  RANK() OVER(ORDER BY val DESC) AS rnk
FROM Sales.OrderValues
QUALIFY rnk <= 5;

標準SQL沒用定義qualify子句，它是Teredata特有的特性。

2.window

允許我們對視窗進行命名描述；然後在定義其他視窗-即將被串鉤函式使用或用來定義另一個命名視窗時，代指這個命名的視窗描述。

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縮寫前置查詢

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吧一個帶有分割槽，排序和框架選項的完整的視窗描述為w1