From b4473220f0f50a9ce2463b3a98a77bf2fdd897af Mon Sep 17 00:00:00 2001
From: Jo <46752250+georgesittas@users.noreply.github.com>
Date: Wed, 15 Jan 2025 01:53:49 +0200
Subject: [PATCH] Chore: parser accepts ctes without as keyword again, except
 for clickhouse (#4612)

---
 sqlglot/dialects/clickhouse.py   | 1 +
 sqlglot/dialects/spark.py        | 2 --
 sqlglot/parser.py                | 2 +-
 tests/dialects/test_snowflake.py | 4 ++++
 4 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/sqlglot/dialects/clickhouse.py b/sqlglot/dialects/clickhouse.py
index 2b8b1e882a..86c0b6b708 100644
--- a/sqlglot/dialects/clickhouse.py
+++ b/sqlglot/dialects/clickhouse.py
@@ -245,6 +245,7 @@ class Parser(parser.Parser):
         # * select x from t1 union all (select x from t2 limit 1);
         MODIFIERS_ATTACHED_TO_SET_OP = False
         INTERVAL_SPANS = False
+        OPTIONAL_ALIAS_TOKEN_CTE = False
 
         FUNCTIONS = {
             **parser.Parser.FUNCTIONS,
diff --git a/sqlglot/dialects/spark.py b/sqlglot/dialects/spark.py
index c84632f28f..08d99e4e51 100644
--- a/sqlglot/dialects/spark.py
+++ b/sqlglot/dialects/spark.py
@@ -102,8 +102,6 @@ class Tokenizer(Spark2.Tokenizer):
         ]
 
     class Parser(Spark2.Parser):
-        OPTIONAL_ALIAS_TOKEN_CTE = True
-
         FUNCTIONS = {
             **Spark2.Parser.FUNCTIONS,
             "ANY_VALUE": _build_with_ignore_nulls(exp.AnyValue),
diff --git a/sqlglot/parser.py b/sqlglot/parser.py
index 9e0d50069a..7f310b3b58 100644
--- a/sqlglot/parser.py
+++ b/sqlglot/parser.py
@@ -1413,7 +1413,7 @@ class Parser(metaclass=_Parser):
     WRAPPED_TRANSFORM_COLUMN_CONSTRAINT = True
 
     # Whether the 'AS' keyword is optional in the CTE definition syntax
-    OPTIONAL_ALIAS_TOKEN_CTE = False
+    OPTIONAL_ALIAS_TOKEN_CTE = True
 
     __slots__ = (
         "error_level",
diff --git a/tests/dialects/test_snowflake.py b/tests/dialects/test_snowflake.py
index 9539071cf0..5c0cc010ea 100644
--- a/tests/dialects/test_snowflake.py
+++ b/tests/dialects/test_snowflake.py
@@ -105,6 +105,10 @@ def test_snowflake(self):
         self.validate_identity(
             "SELECT * FROM DATA AS DATA_L ASOF JOIN DATA AS DATA_R MATCH_CONDITION (DATA_L.VAL > DATA_R.VAL) ON DATA_L.ID = DATA_R.ID"
         )
+        self.validate_identity(
+            "WITH t (SELECT 1 AS c) SELECT c FROM t",
+            "WITH t AS (SELECT 1 AS c) SELECT c FROM t",
+        )
         self.validate_identity(
             "GET_PATH(json_data, '$id')",
             """GET_PATH(json_data, '["$id"]')""",