WINDOW 子句

适用于： Databricks SQL Databricks Runtime

window 子句允许定义并命名一次或多个不同的 window 规范，并在同一查询中的多个 window 函数之间共享它们。

语法

WINDOW { window_name AS window_spec } [, ...]

Parameters

• window_name

  一个 identifier，可通过它引用 window 规范。 identifier 在 WINDOW 子句中必须是唯一的。

• window_spec

  要跨一个或多个 window 函数共享的 window 规范。

示例

> CREATE TABLE employees
   (name STRING, dept STRING, salary INT, age INT);
> INSERT INTO employees
   VALUES ('Lisa', 'Sales', 10000, 35),
          ('Evan', 'Sales', 32000, 38),
          ('Fred', 'Engineering', 21000, 28),
          ('Alex', 'Sales', 30000, 33),
          ('Tom', 'Engineering', 23000, 33),
          ('Jane', 'Marketing', 29000, 28),
          ('Jeff', 'Marketing', 35000, 38),
          ('Paul', 'Engineering', 29000, 23),
          ('Chloe', 'Engineering', 23000, 25);

> SELECT round(avg(age) OVER win, 1) AS salary,
         round(avg(salary) OVER win, 1) AS avgsalary,
         min(salary) OVER win AS minsalary,
         max(salary) OVER win AS maxsalary,
         count(1) OVER win AS numEmps
    FROM employees
    WINDOW win AS (ORDER BY age
                   ROWS BETWEEN 2 PRECEDING AND 2 FOLLOWING);
25.3    27000.0 23000   29000   3
26.0    25500.0 21000   29000   4
27.4    25000.0 21000   29000   5
29.4    25200.0 21000   30000   5
31.4    22600.0 10000   30000   5
33.4    23800.0 10000   35000   5
35.4    26000.0 10000   35000   5
36.0    26750.0 10000   35000   4
37.0    25666.7 10000   35000   3

相关文章

• Window 函数
• SELECT