sqlalchemy.exc.IntegrityError: (pymysql.err.IntegrityError) (1215, 'Cannot add f

oreign key constraint') [SQL: 'ALTER TABLE users ADD FOREIGN KEY(user_group) REF

ERENCES groups (id)']

 SHOW ENGINE INNODB STATUS

| InnoDB |      |

=====================================

2016-11-28 14:15:30 18c4 INNODB MONITOR OUTPUT

=====================================

Per second averages calculated from the last 31 seconds

-----------------

BACKGROUND THREAD

-----------------

srv_master_thread loops: 33 srv_active, 0 srv_shutdown, 19178 srv_idle

srv_master_thread log flush and writes: 19211

----------

SEMAPHORES

----------

OS WAIT ARRAY INFO: reservation count 45

OS WAIT ARRAY INFO: signal count 47

Mutex spin waits 19, rounds 237, OS waits 7

RW-shared spins 31, rounds 930, OS waits 31

RW-excl spins 5, rounds 214, OS waits 7

Spin rounds per wait: 12.47 mutex, 30.00 RW-shared, 42.80 RW-excl

------------------------

LATEST FOREIGN KEY ERROR

------------------------

2016-11-28 13:59:59 18c4 Error in foreign key constraint of table flask/#sql-69c

_30:

FOREIGN KEY(user_group) REFERENCES groups (id):

Cannot find an index in the referenced table where the

referenced columns appear as the first columns, or column types

in the table and the referenced table do not match for constraint.

Note that the internal storage type of ENUM and SET changed in

tables created with >= InnoDB-4.1.12, and such columns in old tables

cannot be referenced by such columns in new tables.

See http://dev.mysql.com/doc/refman/5.6/en/innodb-foreign-key-constraints.html

for correct foreign key definition.

----------------------------------------

END OF INNODB MONITOR OUTPUT

============================

 |

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1.删除project内的migrations文件夹

2.python runserver.py db init

3.python runserver.py db migrate -m "write some words"

4.python runserver.py db upgrade