方式1：
import pymysql
conn = pymysql.connect(host='127.0.0.1',
user='root',
password='123456',
port=3306)
cursor = conn.cursor()
cursor.execute('show databases;')
for item in cursor.fetchall():
print(type(item), item) # item 是 tuple 元组
cursor.close()
conn.close()
运行结果示例：
<class 'tuple'> ('information_schema',)
<class 'tuple'> ('mysql',)
<class 'tuple'> ('performance_schema',)
<class 'tuple'> ('school',)
<class 'tuple'> ('test',)
方式2：
查询结果可以是 dict 类型，不过需要生成 cursor 时指定 cursor 参数为 pymysql.cursors.DictCursor 。
import pymysql
conn = pymysql.connect(host='127.0.0.1',
user='root',
password='123456',
port=3306)
cursor = conn.cursor(cursor=pymysql.cursors.DictCursor) # 指定 cursor 后，结果会被处理为 dict
cursor.execute('show databases;')
for item in cursor.fetchall():
print(type(item), item)
cursor.close()
conn.close()
运行结果示例：
<class 'dict'> {'Database': 'information_schema'}
<class 'dict'> {'Database': 'mysql'}
<class 'dict'> {'Database': 'performance_schema'}
<class 'dict'> {'Database': 'school'}
<class 'dict'> {'Database': 'test'}