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sql - SQL Netezza 中的 SYS_CALENDAR 函数

问题描述

请

如何运行在 SQL Netezza 中生成日历的查询，如下面的与 Teradata 一起使用的查询

SELECT *
   FROM SYS_CALENDAR.Calendar
   where calendar_date BETWEEN '2021-01-01' and current_date

标签： sqlnetezzasys

解决方案

Teradata在和SYS_CALENDAR.Calendar之间的每个日期都有一行。最好重新创建一次，然后在 Netezza 中使用视图1900-01-012100-12-31

一次性初始化

-- A one time table to house all dates between 1900 and 2100
create table t_calendar (dt date);

-- Insert all dates once. Alternatively this SQL can be used
-- in the view, but that will slow things down
INSERT INTO T_CALENDAR 
  SELECT '1900-01-01'::DATE + 
   (10000*a.idx + 1000*b.idx + 100*c.idx + 10*d.idx + e.idx) AS dt
  FROM   _v_vector_idx a,
         _v_vector_idx b,
         _v_vector_idx c,
         _v_vector_idx d,
         _v_vector_idx e
  WHERE  a.idx < 8 -- there are less than 80000 days between 1900-2100
       AND b.idx < 10
       AND c.idx < 10
       AND d.idx < 10
       AND e.idx < 10
       AND dt <= '2100-12-31' :: DATE

完成后，日历视图可以定义如下

create or replace view calendar as
  select 
    dt as calendar_date, 
    date_part('dow', dt) as day_of_week,
    date_part('day', dt) as day_of_month,
    date_part('doy', dt) as day_of_year,
    date_part('days', '1900-01-01'::date - dt) as day_of_calendar
    -- add others as necessary
  from t_calendar

根据需要使用视图定义和Netezza 日期函数向该视图添加更多列。

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