Encapsulation code for database tool classes in Python

Encapsulation of database tool classes.

Purpose of packaging:

• Encapsulate commonly used database operations into a method. When operating the database in the future, call this method to achieve
• Improve code reusability

Design database tool class.

Get Close Connection.

import pymysql
class DBUtil:
#define class attributes to address the issue of yellow reporting 
conn = None
#linking databases 
@classmethod
def __connect_db(cls):
  cls.conn = pymysql.connect(host="211.103.136.244", port=7061, user="student", password="iHRM_student_2022",
                             database="test_db", charset="utf8")
  return cls.conn
#close database 
@classmethod
def __close_db(cls):
  cls.conn.close()  #class properties can directly call methods without prompting 
#method of encapsulation reading 
@classmethod
def query_db(cls, sql):
  result = None
  cursor = None
  try:
      #create a link to the database 
      cls.conn = cls.__connect_db()
      #get cursor 
      cursor = cls.conn.cursor()
      #implement sql,return query results 
      cursor.execute(sql)
      result = cursor.fetchone()  #extract the first row 
  except Exception as err:
      print("error reading database :", err)
  finally:
      #close cursor 
      cursor.close()
      #close link 
      cls.__close_db()
      return result
#methods for packaging, adding, deleting, and modifying 
@classmethod
def update_db(cls, sql):
  cursor = None
  try:
      #create a link to the database 
      cls.conn = cls.__connect_db()
      #get cursor 
      cursor = cls.conn.cursor()
      #implement sql print the number of affected rows 
      cursor.execute(sql)
      affect_rows = cls.conn.affected_rows()
      print("the number of rows affecting the database :", affect_rows)
      #submission and rollback of transactions 
      cls.conn.commit()
  except Exception as err:
      #rollback of transactions 
      cls.conn.rollback()
      print("add, delete, modify database error message :", err)
      pass
  finally:
      #close cursor 
      cursor.close()
      #close link 
      cls.__close_db()
if __name__== '__main__':
res1 = DBUtil.query_db("select  * from t_book  ;")
print(res1)
DBUtil.update_db("insert into t_book (id,title,pub_date) VALUES(1256345253,'iron man','2022-5-1');")
res2 = DBUtil.query_db("select  * from t_book where id = 10145253  ;")
print(res2)
pass
```python
 running results 
(2, 'journey to the west', datetime.date(1980, 1, 1), 1, 0, 0)
 the number of rows affecting the database : 1
(1255, 'iron man', datetime.date(2022, 5, 1), 0, 0, 0)