superset Database on mysql Unexpected error name '_mysql' is not defined

A clear and concise description of what the bug is.

i install superset on MacOS 10.15.5 when i want to add the DB source of mysql, i click the button of [Test Connection],they out the error message

ERROR: Unexpected error occurred, please check your logs for details

then i see the console out the error info

Unexpected error name '_mysql' is not defined
ERROR:superset.views.core:Unexpected error name '_mysql' is not defined
INFO:werkzeug:127.0.0.1 - - [22/Jul/2020 23:10:09] "POST /superset/testconn HTTP/1.1" 400 -

Expected results

i don’t know what to do, please tell me what to do.

Actual results

Screenshots

How to reproduce the bug

1. when i running the cmd of start superset and visit the web http://localhost:8088/,
2. use the menu – > Sources --> Databases, input something then Click on ‘Test Connection’
3. Scroll down to ‘…’
4. See error

Unexpected error name '_mysql' is not defined
ERROR:superset.views.core:Unexpected error name '_mysql' is not defined
INFO:werkzeug:127.0.0.1 - - [22/Jul/2020 23:10:09] "POST /superset/testconn HTTP/1.1" 400 -

Environment

(please complete the following information):

• superset version: superset 0.36.0
• python version: Python 3.7.7
• node.js version: node v12.10.0
• npm version: npm v6.11.3
• mysql version:mysql 8.0.19
• mysqlclient version:mysqlclient 2.0.1
• mysql-connector-python version:mysql-connector-python 8.0.21

Checklist

Make sure these boxes are checked before submitting your issue - thank you!

• I have checked the superset logs for python stacktraces and included it here as text if there are any.
• I have reproduced the issue with at least the latest released version of superset.
• I have checked the issue tracker for the same issue and I haven’t found one similar.

Additional context

Add any other context about the problem here.

[liuyuchuan]

OMG! The problem is solved after i installed the pymysql driver like this: pip install pymysql then i use the SQLAlchemy URI like this: mysql+pymysql://root:Root1234@127.0.0.1:3306/superset

and i use the uri like this is work too. mysql+mysqlconnector://root:Root1234@127.0.0.1:3306/superset

i want to know why i can’t use the SQLAlchemy URI like this:

mysql+mysqldb://root:Root1234@127.0.0.1:3306/superset
or
mysql://root:Root1234@127.0.0.1:3306/superset

[fly904021125]

OMG! The problem is solved after i installed the pymysql driver like this: pip install pymysql then i use the SQLAlchemy URI like this: mysql+pymysql://root:Root1234@127.0.0.1:3306/superset

and i use the uri like this is work too. mysql+mysqlconnector://root:Root1234@127.0.0.1:3306/superset

i want to know why i can’t use the SQLAlchemy URI like this:

mysql+mysqldb://root:Root1234@127.0.0.1:3306/superset
or
mysql://root:Root1234@127.0.0.1:3306/superset

it also works for me.