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#!/usr/bin/env python

#

# Copyright (C) 2009-2020 the sqlparse authors and contributors

# <see AUTHORS file>

#

# This example is part of python-sqlparse and is released under

# the BSD License: https://opensource.org/licenses/BSD-3-Clause

#

# This example illustrates how to extract table names from nested

# SELECT statements.

#

# See:

# https://groups.google.com/forum/#!forum/sqlparse/browse_thread/thread/b0bd9a022e9d4895

import sqlparse

from sqlparse.sql import IdentifierList, Identifier

from sqlparse.tokens import Keyword, DML

def is_subselect(parsed):

if not parsed.is_group:

return False

for item in parsed.tokens:

if item.ttype is DML and item.value.upper() == 'SELECT':

return True

return False

def extract_from_part(parsed):

from_seen = False

for item in parsed.tokens:

if from_seen:

if is_subselect(item):

yield from extract_from_part(item)

elif item.ttype is Keyword:

return

else:

yield item

elif item.ttype is Keyword and item.value.upper() == 'FROM':

from_seen = True

def extract_table_identifiers(token_stream):

for item in token_stream:

if isinstance(item, IdentifierList):

for identifier in item.get_identifiers():

yield identifier.get_name()

elif isinstance(item, Identifier):

yield item.get_name()

# It's a bug to check for Keyword here, but in the example

# above some tables names are identified as keywords...

elif item.ttype is Keyword:

yield item.value

def extract_tables(sql):

stream = extract_from_part(sqlparse.parse(sql)[0])

return list(extract_table_identifiers(stream))

if __name__ == '__main__':

sql = """

select K.a,K.b from (select H.b from (select G.c from (select F.d from

(select E.e from A, B, C, D, E), F), G), H), I, J, K order by 1,2;

"""

tables = ', '.join(extract_tables(sql))

print('Tables: {}'.format(tables))