sql alchemy inconsistant error on program close

import mysql as db

#set up connection to mysql
engine = db.create_engine(CORRECT CONNECTION INFO)
con = engine.connect()
con.close()
exit()

DataTables warning: table id = userTable - (cx_Oracle.DatabaseError) ORA - 00932: inconsistent datatypes: expected - got CLOB[SQL: SELECT count( * ) AS count_1 FROM(SELECT users.fname AS users_fname FROM users WHERE lower(CAST(users.fname AS CLOB)) LIKE lower(: param_1)) anon_1]
   [parameters: {
      'param_1': '%a%'
   }]

engine = create_engine("mysql://u:p@host/db", pool_size = 10, max_overflow = 20)

>>> from sqlalchemy
import column
   >>>
   print(column('x') == 5)
x =: x_1

>>> from sqlalchemy.dialects.postgresql import insert
>>> from sqlalchemy import table, column
>>> my_table = table('my_table', column('x'), column('y'))
>>> insert_stmt = insert(my_table).values(x='foo')
>>> insert_stmt = insert_stmt.on_conflict_do_nothing(
... index_elements=['y']
... )
>>> print(insert_stmt)
Traceback (most recent call last):

...

sqlalchemy.exc.UnsupportedCompilationError:
Compiler <sqlalchemy.sql.compiler.StrSQLCompiler object at 0x7f04fc17e320>
   can't render element of type
   <class 'sqlalchemy.dialects.postgresql.dml.OnConflictDoNothing'>

>>> from sqlalchemy.dialects
import postgresql
   >>>
   print(insert_stmt.compile(dialect = postgresql.dialect()))
INSERT INTO my_table(x) VALUES( % (x) s) ON CONFLICT(y) DO NOTHING

statement = query.statement
print(statement.compile(dialect = postgresql.dialect()))

class Bar(Base):
   __tablename__ = 'bar'

id = Column(Integer, primary_key = True)
cprop = deferred(Column(Integer))

__table_args__ = (
   CheckConstraint(cprop > 5),
)

pip install--upgrade snowflake - sqlalchemy

#!/usr/bin/env python
from sqlalchemy import create_engine

engine = create_engine(
    'snowflake://{user}:{password}@{account_identifier}/'.format(
        user='<user_login_name>',
        password='<password>',
        account_identifier='<account_identifier>',
    )
)
try:
    connection = engine.connect()
    results = connection.execute('select current_version()').fetchone()
    print(results[0])
finally:
    connection.close()
    engine.dispose()

python validate.py

'snowflake://<user_login_name>:<password>@<account_identifier>'

'snowflake://<user_login_name>:<password>@<account_identifier>/<database_name>/<schema_name>?warehouse=<warehouse_name>&role=<role_name>'

from sqlalchemy
import create_engine
engine = create_engine(
   'snowflake://testuser1:0123456@myorganization-myaccount/testdb/public?warehouse=testwh&role=myrole'
)

(venv) $ flask db migrate - m "remove a column"

""
"remove a column

Revision ID: ec813e760b53
Revises: 834 b1a697901
Create Date: 2020 - 07 - 19 18: 18: 44.066766

""
"
from alembic
import op
import sqlalchemy as sa

# revision identifiers, used by Alembic.
revision = 'ec813e760b53'
down_revision = '834b1a697901'
branch_labels = None
depends_on = None

def upgrade():
   # # # # commands auto generated by Alembic - please adjust!# # #
op.drop_column('user', 'about_me')
# # # # end Alembic commands # # #

def downgrade():
   # # # # commands auto generated by Alembic - please adjust!# # #
op.add_column('user', sa.Column('about_me', sa.VARCHAR(length = 140), nullable = True))
# # # # end Alembic commands # # #

(venv) $ flask db upgrade
   [2020 - 07 - 19 18: 21: 14, 268] INFO in __init__: Microblog startup
INFO[alembic.runtime.migration] Context impl SQLiteImpl.
INFO[alembic.runtime.migration] Will assume non - transactional DDL.
INFO[alembic.runtime.migration] Running upgrade 834 b1a697901 - > ec813e760b53, remove a column
Traceback(most recent call last):
   File "/Users/mgrinberg/Documents/dev/python/microblog/venv/lib/python3.8/site-packages/sqlalchemy/engine/base.py", line 1283, in _execute_context
self.dialect.do_execute(
      File "/Users/mgrinberg/Documents/dev/python/microblog/venv/lib/python3.8/site-packages/sqlalchemy/engine/default.py", line 590, in do_execute cursor.execute(statement, parameters) sqlite3.OperationalError: near "DROP": syntax error

      The above exception was the direct cause of the following exception:

      Traceback(most recent call last): [...removed a long list of uninteresting stack frames...] sqlalchemy.exc.OperationalError: (sqlite3.OperationalError) near "DROP": syntax error[SQL: ALTER TABLE user DROP COLUMN about_me]
      (Background on this error at: http: //sqlalche.me/e/e3q8)

migrate = Migrate()

def create_app():
   #...
   migrate.init_app(app, db, render_as_batch = True)
#...

(venv) $ flask db migrate - m "remove a column"

Thanks Miguel!And that Flask - Migrate batch configuration was the option all the time ? Hours of rewriting migrate scripts with SQLite db...

Thank you
for this excellent piece of information!I had been struggling with this issue in the back of my mind off and on
for awhile in a "for fun"
project I 've been working on while learning Flask.  I was glad to find your post because it directly addressed my issue and provided a solution!

Thank you so much
for this!Such a simple fix: )

This worked really well.Is there a reason to revert back to non - batch mode ? Or is this the ideal
default
for any migration ?

Fantastic!Thank you!

myfunction(x, y):
   return x + y

else:
   print("Hello!")

if mark >= 50
print("You passed!")

if arriving:
   print("Hi!")
esle:
   print("Bye!")

if flag:
   print("Flag is set!")

dividend = float(input("Please enter the dividend: "))
divisor = float(input("Please enter the divisor: "))
quotient = dividend / divisor
quotient_rounded = math.round(quotient)

for x in range(a, b):
   print("(%f, %f, %f)" % my_list[x])

product = 0
for i in range(10):
   product *= i

sum_squares = 0
for i in range(10):
   i_sq = i ** 2
sum_squares += i_sq

nums = 0
for num in range(10):
   num += num

try:
age = int(input("Please enter your age: "))
print("I see that you are %d years old." % age)
except ValueError:
   print("Hey, that wasn't a number!")

try:
dividend = int(input("Please enter the dividend: "))
divisor = int(input("Please enter the divisor: "))
print("%d / %d = %f" % (dividend, divisor, dividend / divisor))
except(ValueError, ZeroDivisionError):
   print("Oops, something went wrong!")

>>> print "hello"
SyntaxError: Missing parentheses in call to 'print'.Did you mean print("hello") ?

>>> L1=[1,2,3]
>>> L1[3]
Traceback (most recent call last):
File "<pyshell#18>", line 1, in <module>

      L1[3]
      IndexError: list index out of range

>>> import notamodule
Traceback (most recent call last):
File "<pyshell#10>", line 1, in <module>

      import notamodule
      ModuleNotFoundError: No module named 'notamodule'

>>> D1={'1':"aa", '2':"bb", '3':"cc"}
>>> D1['4']
Traceback (most recent call last):
File "<pyshell#15>", line 1, in <module>

            
D1['4']
KeyError: '4'

>>> from math import cube
Traceback (most recent call last):
File "<pyshell#16>", line 1, in <module>

      from math import cube
      ImportError: cannot import name 'cube'

>>> it=iter([1,2,3])
>>> next(it)
1
>>> next(it)
2
>>> next(it)
3
>>> next(it)
Traceback (most recent call last):
File "<pyshell#23>", line 1, in <module>

      next(it)
      StopIteration

# This code has an intentional error.You can type it directly or
# use it
for reference to understand the error message below.
def favorite_ice_cream():
   ice_creams = [
      "chocolate",
      "vanilla",
      "strawberry"
   ]
print(ice_creams[3])

favorite_ice_cream()

---------------------------------------------------------------------------
IndexError Traceback (most recent call last)
<ipython-input-1-70bd89baa4df> in <module>()
      6 print(ice_creams[3])
      7
      ----> 8 favorite_ice_cream()

      <ipython-input-1-70bd89baa4df> in favorite_ice_cream()
         4 "vanilla", "strawberry"
         5 ]
         ----> 6 print(ice_creams[3])
         7
         8 favorite_ice_cream()

         IndexError: list index out of range

def some_function()
msg = "hello, world!"
print(msg)
return msg

  File "<ipython-input-3-6bb841ea1423>", line 1
     def some_function()
     ^
     SyntaxError: invalid syntax

def some_function():
   msg = "hello, world!"
print(msg)
return msg

  File "<ipython-input-4-ae290e7659cb>", line 4
     return msg
     ^
     IndentationError: unexpected indent