import pymysql

class MyDb():
  def __init__(self, host, user, passwd, db):
      self.__db = pymysql.connect(host, user, passwd, db)
      self.__cursor = self.__db.cursor()

  # 增删改-数据库
  def set(self, sql):
    try:
      self.__cursor.execute(sql)
      self.__db.commit()
    except Exception as e:
      self.__db.rollback()
      print('Execute Error: \n {e}')

  # 查-数据库
  def get(self, sql, fetchone=True):
    self.__cursor.execute(sql)
    try:
      if fetchone == True:
        data = self.__cursor.fetchone()
      else:
        data = self.__cursor.fetchall()
    except Exception as e:
      print('Execute Error: \n {e}')
      data = None
    finally:
      return data

  # 关闭数据库
  def close(self):
    self.__db.close()

def example():
  ## 实例化数据库
  ### 类参数：host、user、passwd、db
  db = MyDb('localhost', 'root', 'zuoy123', 'test')
  
  ## 查看版本
  get_version_sql = 'SELECT VERSION()'
  version = db.get(get_version_sql)
  print(f'Database Version: {version}')

  ## 删除表
  delete_table_sql = 'DROP TABLE IF EXISTS employee'
  db.set(delete_table_sql)

  ## 新建表
  new_table_sql = 'CREATE TABLE IF NOT EXISTS employee(     id INT NOT NULL PRIMARY KEY,     name CHAR(21) NOT NULL,     age DOUBLE DEFAULT 18)'
  db.set(new_table_sql)

  ## 查找表
  get_table_sql = 'SHOW TABLES'
  data = db.get(get_table_sql)
  if data:
    print(data)

  ## 关闭数据库
  db.close()

if __name__ == '__main__':
  example()

DROP TABLE IF EXISTS employee;
CREATE TABLE IF NOT EXISTS employee(id INT);