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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))
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