postgresql数据库使用说明_实现时间范围查询
(编辑:jimmy 日期: 2024/11/25 浏览:3 次 )
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(data.head()) for i in range(len(data)): #sql = "SELECT * FROM `%s` WHERE `key` = '{}'"%(exchange).format(row.Key) #found = pd.read_sql(sql, con=conn2) #if len(found) == 0: try: data.iloc[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");
补充:postgresql 数据库时间间隔数据查询
当前时间向前推一天:
SELECT current_timestamp - interval '1 day'
当前时间向前推一个月:
SELECT current_timestamp - interval '1 month'
当前时间向前推一年:
SELECT current_timestamp - interval '1 year'
当前时间向前推一小时:
SELECT current_timestamp - interval '1 hour'
当前时间向前推一分钟:
SELECT current_timestamp - interval '1 min'
当前时间向前推60秒:
SELECT current_timestamp - interval '60 second'
以上为个人经验,希望能给大家一个参考,也希望大家多多支持。如有错误或未考虑完全的地方,望不吝赐教。
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