python jdbc操作數據庫

#encoding=utf-8
import pymysql
import student
class jdbc_connect:
    '數據庫執行操作'
    #執行對象
    cursor="";
    db=False;

    #連接數據庫
    def __init__(self,host,username,password,database):
        try:
            jdbc_connect.db = pymysql.connect(host, username,password, database, charset="utf8");
            jdbc_connect.cursor = self.db.cursor();
        except BaseException:
            print("連接數據庫異常")
            self.db.close()


    '查詢數據庫 並且返還對象'
    def  select(self,sql):
        jdbc_connect.cursor.execute(sql);
        students=self.cursor.fetchall();
        return students;


    '向數據庫添加數據'
    '0成功/1失敗'
    def insert(self,sql):
       try:
        jdbc_connect.cursor.execute(sql);
        jdbc_connect.db.commit();
       except pymysql.DataError:
            jdbc_connect.db.rollback();
            print("執行添加操作失敗")
            return "1"
       else:
           return "0"
    '修改'
    def update(self,sql):
        try:
            jdbc_connect.cursor.execute(sql);
            jdbc_connect.db.commit();
        except pymysql.DataError:
            jdbc_connect.db.rollback();
            print("執行修改操作失敗")
            return "1"
        else:
            return "0"
    '刪除'
    def delete(self,sql):
        try:
            jdbc_connect.cursor.execute(sql);
            jdbc_connect.db.commit();
        except pymysql.DataError:
            jdbc_connect.db.rollback();
            print("執行刪除操作失敗")
            return "1"
        else:
            return "0"
    '關閉數據庫連接'
    def closedb(self):
        try:
            self.cursor.close();
            self.db.close();
        except BaseException:
            print("db close error")


-------調用---------

import student
import jdbc_connect

dbt=jdbc_connect.jdbc_connect("localhost", "root", "ok", "pythontest")
str1="select * from student"
#學生集合
students=dbt.select(str1)
print(students)
# insert_str="insert into student values('王五1',18,'sa51df321s')"
# print(dbt.insert(insert_str)
# print(students))
# students=dbt.select(str1)
# update_str="update student set name='王二麻子' where name='王五'"
# print(dbt.update(update_str))

delete_str="delete from student where name='王二麻子'"
dbt.delete(delete_str)
print(dbt.select(str1))