postgresql数据库使用——时间范围查询

时间：2024-10-18 07:42:23

postgresql按照日期范围进行查询

按照日期查询通常有好几种方法：

按照日期范围查询有好几种方法，日期字段类型一般为：

Timestamp without timezone
方法一：
select * from user_info where create_date
>= '2015-07-01' and create_date < '2015-08-15';

方法二：
select * from user_info where create_date
between '2015-07-01' and '2015-08-15';

方法三：
select * from user_info where create_date
>= '2015-07-01'::timestamp and create_date < '2015-08-15'::timestamp;

方法四：


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');

pandas.to_sql 遇到主键重复的，怎么能够跳过继续执行呢，其实很简单，就一条一条的插入就可以了，因为to_sql还没有很好的解决办法。

具体的代码如下所示：

    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 无法设置主键，这个是肯定的，能做的办法就是在to_sql之前先使用创建表的方法，创建一张表

建表的代码如下所示：

/*
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");

 

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