Postgresql database usage instructions_Implement time range query

There are usually several ways to query by date:

There are several methods for querying by date range, and the date field type is generally:

Timestamp without timezone

Method 1:

select * from user_info where create_date
>= '2015-07-01' and create_date < '2015-08-15';

Method 2:

select * from user_info where create_date
between '2015-07-01' and '2015-08-15';

Method 3:

select * from user_info where create_date
>= '2015-07-01'::timestamp and create_date < '2015-08-15'::timestamp;

Method 4:

 
select * from user_info where create_date
between to_date('2015-07-01','YYYY-MM-DD') and to_date('2015-08-15','YYYY-MM-DD');

When pandas.to_sql encounters duplicate primary key, how can you skip and continue execution? It is actually very simple, just insert one by one, because to_sql does not have a good solution.

The specific code is as follows:

  for exchange in exchange_list.items():
    if exchange[1]==True:
      pass
    else:
      continue
    sql = """ SELECT * FROM %s WHERE "time" BETWEEN '2019-07-05 18:48' AND '2019-07-09' """ % (exchange[0])
    data = pd.read_sql(sql=sql, con=conn)
    print(())
    for i in range(len(data)):
      #sql = "SELECT * FROM `%s` WHERE `key` = '{}'"%(exchange).format()
      #found = pd.read_sql(sql, con=conn2)
      #if len(found) == 0:
      try:
        [i:i + 1].to_sql(name=exchange[0], index=False,if_exists='append', con=conn2)
      except Exception as e:
        print(e)
        pass

pandas.to_sql cannot set the primary key, this is certain. The method that can be done is to use the method of creating a table before to_sql to create a table

The code for building a table is as follows:

/*
Create SEQUENCE for table
*/
DROP SEQUENCE IF EXISTS @exchangeName_id_seq;
CREATE SEQUENCE @exchangeName_id_seq
START WITH 1
INCREMENT BY 1
NO MINVALUE
NO MAXVALUE
CACHE 1;
 
/*
Create Table structure for table
*/
DROP TABLE IF EXISTS "public"."@exchangeName";
CREATE TABLE "public"."@exchangeName" (
 "id" int4 NOT NULL DEFAULT nextval('@exchangeName_id_seq'::regclass),
 "time" timestamp(6) NOT NULL,
 "open" float8,
 "high" float8,
 "low" float8,
 "close" float8,
 "volume" float8,
 "info" varchar COLLATE "pg_catalog"."default" NOT NULL
)
;
 
/*
Create Primary Key structure for table
*/
ALTER TABLE "public"."@exchangeName" DROP CONSTRAINT IF EXISTS "@exchangeName_pkey";
ALTER TABLE "public"."@exchangeName" ADD CONSTRAINT "@exchangeName_pkey" PRIMARY KEY ("time", "info");

Supplement: Postgresql database time interval data query

The current time is pushed forward one day:

SELECT current_timestamp - interval '1 day'

The current time is pushed forward by one month:

SELECT current_timestamp - interval '1 month'

The current time is one year ahead:

SELECT current_timestamp - interval '1 year'

The current time is pushed forward by one hour:

SELECT current_timestamp - interval '1 hour'

Push the current time forward by one minute:

SELECT current_timestamp - interval '1 min'

The current time is pushed forward by 60 seconds:

SELECT current_timestamp - interval '60 second'

The above is personal experience. I hope you can give you a reference and I hope you can support me more. If there are any mistakes or no complete considerations, I would like to give you advice.