python中进行sql查询出现乱码怎么解决

import pymysql

db=pymysql.connect(host="localhost",user="root",password="root",database="school_schema",charset="GBK")

cursor=db.cursor()

sqlstr="SELECT * FROM school_schema.course;"try:

    cursor.execute(sqlstr)

    courses=cursor.fetchall()except:

    print("数据读取错误")else:

    print(courses)

db.close()