PostgreSQL

Posted 2022-09-03 lonelyrains

# PostgreSQL Schema

--查所有数据表

SELECT
  tables.table_name, 
  tables.table_schema, 
  tables.table_type
FROM
  information_schema.tables
Where
  tables.table_name like '%DATA_HISTORY%'
order by tables.table_name

--查数据表的所有字段

SELECT
    *,
    column_name,
    data_type
FROM
    information_schema.columns
WHERE
    table_name = 'DATA_HISTORY_20211025_001';

-- 查字段值

SELECT 
  "DATA_HISTORY_2020"."time", 
  "DATA_HISTORY_2020"."data1", 
  "DATA_HISTORY_2020"."data2", 
FROM 
  public."DATA_HISTORY_2020", 

-- 查字段值

SELECT time,"data1" 
FROM "DATA_HISTORY_2021" 
WHERE time >= 637708000000000000 And time <=637709000000000000

# bigint datetime 转换 

PostgreSQL: Re: Datetime stored in bigint

CREATE OR REPLACE FUNCTION yearzero_to_timestamp(BIGINT)
RETURNS TIMESTAMP
IMMUTABLE
LANGUAGE SQL
AS $bc$
  SELECT '0001-01-01'::date + ('1 hour'::interval * (SELECT $1/10000000/60.0/60.0));
$bc$;


SELECT yearzero_to_timestamp(634459985818906250);

上面超链接的代码，有个bug是，秒显示为0。下面的代码

SELECT $1/10000000/60/60.0

要改为

SELECT $1/10000000/60.0/60