python 插入Null值数据到Postgresql的操作

python 插入Null值数据到Postgresql的操作

数据库中最好插入Null值。

在python中,暂时没找到通过sql语句的方式插入Null值。

推荐使用轮子的方法

def insert_sample_data(self, values): # added self since you are referencing it below
 with self.con.cursor() as cur:
  sql = "insert into sampletable values (%s, %s, %s)" # Use %s for parameters
  cur.executemany(sql, values) # Pass the list of tuples directly
  self.con.commit()
 
list1 = [(1100, "abc", "{"1209": "Y", "1210": "Y"}"), (1100, "abc", None)]
self.insert_sample_data(list1) # pass the list directly

补充:python连接数据库插入数据库数据所碰到的坑

Python中插入数据时执行后,没有报任何错误,但数据库中并没有出现新添加的数据

原因:

缺少提交操作。

解决方案:

Python操作数据库时,如果对数据表进行修改/删除/添加等控制操作,系统会将操作保存在内存,只有执行commit(),才会将操作提交到数据库。

但是总有你想不到的坑代码如下:

import pymysql 
class Connection: 
 def __init__(self):
  self.host = "localhost"
  self.user = "nameit"
  self.password = "YES"
  self.port = 3306
  self.db = "Xomai" 
 
 def connection(self): 
  db = pymysql.connect(host=self.host, user=self.user, password=self.password, port=self.port, db=self.db)
  cur = db.cursor()
  return db, cur
 
 def create_table(self, cur): 
  sql = """CREATE TABLE `activity_feedback` (
     `id` bigint(20) NOT NULL AUTO_INCREMENT,
     `inst_id` bigint(20) DEFAULT NULL COMMENT "ID",
     `broadcast_id` bigint(20) DEFAULT NULL COMMENT "你好",
     `student_id` bigint(20) DEFAULT NULL COMMENT "学生ID",
     `content` varchar(1024) DEFAULT NULL COMMENT "学员内容",
     `comment` varchar(255) DEFAULT NULL COMMENT "注释",
     `gmt_create` datetime DEFAULT NULL,
     `gmt_modify` datetime DEFAULT NULL,
     PRIMARY KEY (`id`),
     KEY `activity_feedback_student_id_index` (`student_id`)
    ) ENGINE = InnoDB AUTO_INCREMENT = 1050 DEFAULT CHARSET = utf8mb4 COMMENT = "学员表""""
  cur.execute(sql)
 def insert(self, id, inst_id, broadcast_id, student_id, content, comment, gmt_create, gmt_modify):
  sql = """INSERT INTO `activity_feedback` (
     `id`, `inst_id`, `broadcast_id`, `student_id`, `content`, `comment`, `gmt_create`, `gmt_modify`)
     VALUES ("{}","{}","{}","{}","{}","{}","{}","{}")""".format(id, inst_id, broadcast_id, student_id, content, comment, gmt_create, gmt_modify)
  try:
   self.connection()[1].execute(sql)
   self.connection()[0].commit()
  except:
   self.connection()[0].rollback()
if __name__ == "__main__":
 conn = Connection()
 conn.insert(123, 123, 324, 3451, "ajdf", "sdfs", "2013-2-5", "2014-3-4")

咋一看好像也有commit呀,怎么一直在数据库没有,再仔细看看

  try:
   self.connection()[1].execute(sql)
   self.connection()[0].commit()
  except:
   self.connection()[0].rollback()

connection()调用方法方法返回的对象是同一个吗?

并不是,心累,搞了半天,只怪自己还太嫩。

正确写法:

  try:
   cons = self.connection()
   cons[1].execute(sql)
   cons[0].commit()
   cons[0].close()
  except:
   cons[0].rollback()

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云海天教程。如有错误或未考虑完全的地方,望不吝赐教。