从查询批量插入 table (postgresql)

Question

我找不到这个问题的答案:

我想将此查询的结果插入 table 'days':

WITH days AS ( 
SELECT 
date_part('dow',generate_series('2017-11-01','2017-11-30', interval '1 day')) as dow, 
to_char(generate_series('2017-11-01','2017-11-30', interval '1 day'),'YYYY-MM-DD') as date ) 

SELECT 0 as id,date, 
CASE 
WHEN dow=1 then 8 
WHEN dow=2 then 8 
WHEN dow=3 then 8 
WHEN dow=4 then 8 
WHEN dow=5 then 8 
WHEN dow=6 then 0 
WHEN dow=0 then 0 
ELSE 0 END as wtime 
FROM days

table就这么简单：

CREATE TABLE days
    (id serial, dates date, wtime numeric(8,2));

在我的梦想中它应该是这样的：

INSERT * INTO days FROM (

WITH days AS ( 
SELECT 
date_part('dow',generate_series('2017-11-01','2017-11-30', interval '1 day')) as dow, 
to_char(generate_series('2017-11-01','2017-11-30', interval '1 day'),'YYYY-MM-DD') as date ) 

SELECT 0 as id,date, 
CASE 
WHEN dow=1 then 8 
WHEN dow=2 then 8 
WHEN dow=3 then 8 
WHEN dow=4 then 8 
WHEN dow=5 then 8 
WHEN dow=6 then 0 
WHEN dow=0 then 0 
ELSE 0 END as wtime 
FROM days)

这可能吗？怎么样？

http://sqlfiddle.com/#!15/91c720/8

Answer 1

CTE (WITH) 需要先出现，然后是插入。您还需要为 CTE 指定一个不同的名称，否则名称 days 会产生歧义

with gen_days (
...)
insert into days 
select *
from gen_days;

但是您会遇到问题，因为您的查询会为 date 列生成 varchar 值，而不是真正的 DATE 类型。您需要更改它以将 generate_series() 的结果转换为日期。您也只需要一个 generate_series() 而不是两个：

WITH gen_dates AS ( 
 SELECT date_part('dow',d.dt) as dow, 
        dt::date as date
  from generate_series('2017-11-01','2017-11-30', interval '1 day') as d(dt)
) 
insert into days (dates, wtime)
SELECT date, 
       CASE 
         WHEN dow=1 then 8 
         WHEN dow=2 then 8 
         WHEN dow=3 then 8 
         WHEN dow=4 then 8 
         WHEN dow=5 then 8 
         WHEN dow=6 then 0 
         WHEN dow=0 then 0 
         ELSE 0
       END as wtime 
FROM gen_dates

无关，但是：您并不真的需要 CTE。您可以将插入简化为：

insert into days (dates, wtime)
SELECT dt::date, 
       CASE date_part('dow', dt) 
         WHEN 1 then 8 
         WHEN 2 then 8 
         WHEN 3 then 8 
         WHEN 4 then 8 
         WHEN 5 then 8 
         WHEN 6 then 0 
         WHEN 0 then 0 
         ELSE 0
       END as wtime 
FROM generate_series('2017-11-01','2017-11-30', interval '1 day') as d(dt);

请注意 CASE 语句的简短形式，您不必重复测试所针对的表达式。

Answer 2

也许您的问题是 CTE 和您的目标 table 同名。另一个问题是您的 "date" 源列不是真正的 date 数据类型：

INSERT * INTO days
WITH days_cte AS ( 
SELECT 
date_part('dow',generate_series('2017-11-01','2017-11-30', interval '1                     day')) as dow, 
to_char(generate_series('2017-11-01','2017-11-30', interval '1 day'),'YYYY-MM-DD') as date ) 
SELECT 0 as id, "date"::date, 
CASE 
WHEN dow=1 then 8 
WHEN dow=2 then 8 
WHEN dow=3 then 8 
WHEN dow=4 then 8 
WHEN dow=5 then 8 
WHEN dow=6 then 0 
WHEN dow=0 then 0 
ELSE 0 END as wtime 
FROM days_cte

从查询批量插入 table (postgresql)

bulk insert from a query into table (postgresql)

postgresql

postgresql-9.4