clean some old sqlalchemy code

pandas/io/sql.py

@@ -47,24 +47,10 @@ def _is_sqlalchemy_connectable(con):
  try:
  import sqlalchemy
  _SQLALCHEMY_INSTALLED = True
-
- from distutils.version import LooseVersion
- ver = sqlalchemy.__version__
- # For sqlalchemy versions < 0.8.2, the BIGINT type is recognized
- # for a sqlite engine, which results in a warning when trying to
- # read/write a DataFrame with int64 values. (GH7433)
- if LooseVersion(ver) < LooseVersion('0.8.2'):
- from sqlalchemy import BigInteger
- from sqlalchemy.ext.compiler import compiles
-
- @compiles(BigInteger, 'sqlite')
- def compile_big_int_sqlite(type_, compiler, **kw):
- return 'INTEGER'
  except ImportError:
  _SQLALCHEMY_INSTALLED = False
 
  if _SQLALCHEMY_INSTALLED:
- import sqlalchemy
  return isinstance(con, sqlalchemy.engine.Connectable)
  else:
  return False