Requirement already satisfied: pymysql in d:\python\python3.6\lib\site-packages (1.0.2)

 使用 pip install pymysql时，出现：Requirement already satisfied: pymysql in d:\python\python3.6\lib\site-packages (1.0.2)

解决方案：
pip install --target=路径 包名：
pip install --target=d:\python\python3.6\lib\site-packages pymysql

结果：安装成功了，但是出现了警告：
WARNING: Target directory d:\python\python3.6\lib\site-packages\pymysql already exists. Specify --upgrade to force replacement.

解决方案：
意思是已存在，需要强制替换的话就在最后面加--upgrade
pip install --target=d:\python\python3.6\lib\site-packages pymysql --upgrade
结果：