From a594e747a29052ec86a399c7080f6a363225ad97 Mon Sep 17 00:00:00 2001
From: adenzhou1350 <209601943+adenzhou1350@users.noreply.github.com>
Date: Tue, 6 Oct 2026 14:59:01 +0800
Subject: [PATCH] fix: avoid duplicate breaks before aliased subqueries

---
 sqlparse/filters/reindent.py            | 13 ++++-
 tests/test_aliased_subquery_reindent.py | 74 +++++++++++++++++++++++++
 2 files changed, 86 insertions(+), 1 deletion(-)
 create mode 100644 tests/test_aliased_subquery_reindent.py

diff --git a/sqlparse/filters/reindent.py b/sqlparse/filters/reindent.py
index f8f64532..609317d2 100644
--- a/sqlparse/filters/reindent.py
+++ b/sqlparse/filters/reindent.py
@@ -191,7 +191,18 @@ def _process_identifierlist(self, tlist):
                             if comma is None:
                                 continue
                             token = comma
-                        tlist.insert_before(token, self.nl(offset=adjust))
+                        first = (token.token_first()
+                                 if isinstance(token, sql.Identifier)
+                                 else token)
+                        _, query = (first.token_next_by(
+                            t=(T.Keyword.DML, T.Keyword.DDL))
+                            if isinstance(first, sql.Parenthesis)
+                            else (None, None))
+                        # Query parentheses add their own leading newline.
+                        # An alias wraps them in an Identifier, but must not
+                        # cause the list to add a second break before it.
+                        if query is None:
+                            tlist.insert_before(token, self.nl(offset=adjust))
                         if self.comma_first:
                             _, ws = tlist.token_next(
                                 tlist.token_index(token), skip_ws=False)
diff --git a/tests/test_aliased_subquery_reindent.py b/tests/test_aliased_subquery_reindent.py
new file mode 100644
index 00000000..7ef85cf8
--- /dev/null
+++ b/tests/test_aliased_subquery_reindent.py
@@ -0,0 +1,74 @@
+import pytest
+
+import sqlparse
+
+
+@pytest.mark.parametrize('width', [2, 4])
+def test_aliased_subquery_has_one_leading_break(width):
+    # Issue 334: both the IdentifierList and the query Parenthesis added a
+    # newline when an alias wrapped the parenthesis in an Identifier.
+    source = ('select c.id, c.value, '
+              '(select count(*) as cnt from d where d.item_id = id) '
+              'as "Count", c.whatever from something as c')
+    expected = '\n'.join([
+        'SELECT c.id,',
+        '       c.value,',
+        ' ' * width + '(SELECT count(*) AS cnt',
+        ' ' * (width + 1) + 'FROM d',
+        ' ' * (width + 1) + 'WHERE d.item_id = id) AS "Count",',
+        '       c.whatever',
+        'FROM something AS c',
+    ])
+    options = {'reindent': True, 'keyword_case': 'upper', 'indent_width': width}
+    assert sqlparse.format(source, **options) == expected
+    assert sqlparse.format(expected, **options) == expected
+
+
+@pytest.mark.parametrize('alias', ['as counted', 'counted', 'as "Count"'])
+def test_multiple_aliased_query_columns(alias):
+    source = f'select a, (select 1) {alias}, (select 2) othercol, b from tbl'
+    expected = '\n'.join([
+        'select a,',
+        f'  (select 1) {alias},',
+        '  (select 2) othercol,',
+        '       b',
+        'from tbl',
+    ])
+    assert sqlparse.format(source, reindent=True) == expected
+
+
+@pytest.mark.parametrize('source,expected', [
+    ('select (select 1) as counted, c.id from something as c',
+     'select\n  (select 1) as counted,\n       c.id\nfrom something as c'),
+    ('select (select 1) as counted from something as c',
+     'select\n  (select 1) as counted\nfrom something as c'),
+    ('select c.id, (c.value + 1) as counted, c.whatever from something as c',
+     'select c.id,\n       (c.value + 1) as counted,\n'
+     '       c.whatever\nfrom something as c'),
+    ('select * from (select 1) as counted',
+     'select *\nfrom\n  (select 1) as counted'),
+])
+def test_other_parenthesis_layouts_are_unchanged(source, expected):
+    assert sqlparse.format(source, reindent=True) == expected
+
+
+@pytest.mark.parametrize('options,expected', [
+    ({'indent_tabs': True},
+     'select a,\n\t\t(select 1) as counted,\n\tb\nfrom tbl'),
+    ({'indent_columns': True},
+     'select\n  a,\n  (select 1) as counted,\n  b\nfrom tbl'),
+    ({'wrap_after': 100},
+     'select a,\n  (select 1) as counted, b\nfrom tbl'),
+    ({'comma_first': True},
+     'select a\n     ,\n  (select 1) as counted\n     , b\nfrom tbl'),
+])
+def test_aliased_subquery_format_options(options, expected):
+    source = 'select a, (select 1) as counted, b from tbl'
+    assert sqlparse.format(source, reindent=True, **options) == expected
+
+
+def test_statement_separator_blank_line_is_retained():
+    source = 'select a, (select 1) as counted, b from tbl; select 2;'
+    expected = ('select a,\n  (select 1) as counted,\n       b\n'
+                'from tbl;\n\nselect 2;')
+    assert sqlparse.format(source, reindent=True) == expected