From 6c5e6a2735d952fcac6d615079f7cc783a870e92 Mon Sep 17 00:00:00 2001
From: George Sittas <giwrgos.sittas@gmail.com>
Date: Tue, 26 Nov 2024 16:58:29 +0200
Subject: [PATCH] Fix: parse DEFALUT in VALUES clause into a Var

---
 sqlglot/dialects/dialect.py  | 3 +++
 sqlglot/dialects/presto.py   | 1 +
 sqlglot/parser.py            | 7 ++++++-
 tests/dialects/test_mysql.py | 7 +++++++
 4 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/sqlglot/dialects/dialect.py b/sqlglot/dialects/dialect.py
index 5b12f56c0..eca2bf592 100644
--- a/sqlglot/dialects/dialect.py
+++ b/sqlglot/dialects/dialect.py
@@ -411,6 +411,9 @@ class Dialect(metaclass=_Dialect):
     is cast to x's type to match it instead.
     """
 
+    SUPPORTS_VALUES_DEFAULT = True
+    """Whether the DEFAULT keyword is supported in the VALUES clause."""
+
     REGEXP_EXTRACT_DEFAULT_GROUP = 0
     """The default value for the capturing group."""
 
diff --git a/sqlglot/dialects/presto.py b/sqlglot/dialects/presto.py
index ec702a097..056d974c2 100644
--- a/sqlglot/dialects/presto.py
+++ b/sqlglot/dialects/presto.py
@@ -198,6 +198,7 @@ class Presto(Dialect):
     TYPED_DIVISION = True
     TABLESAMPLE_SIZE_IS_PERCENT = True
     LOG_BASE_FIRST: t.Optional[bool] = None
+    SUPPORTS_VALUES_DEFAULT = False
 
     TIME_MAPPING = MySQL.TIME_MAPPING
 
diff --git a/sqlglot/parser.py b/sqlglot/parser.py
index 2a477d9b9..12419e8c2 100644
--- a/sqlglot/parser.py
+++ b/sqlglot/parser.py
@@ -2946,8 +2946,13 @@ def _parse_partition(self) -> t.Optional[exp.Partition]:
         )
 
     def _parse_value(self) -> t.Optional[exp.Tuple]:
+        def _parse_value_expression() -> t.Optional[exp.Expression]:
+            if self.dialect.SUPPORTS_VALUES_DEFAULT and self._match(TokenType.DEFAULT):
+                return exp.var(self._prev.text.upper())
+            return self._parse_expression()
+
         if self._match(TokenType.L_PAREN):
-            expressions = self._parse_csv(self._parse_expression)
+            expressions = self._parse_csv(_parse_value_expression)
             self._match_r_paren()
             return self.expression(exp.Tuple, expressions=expressions)
 
diff --git a/tests/dialects/test_mysql.py b/tests/dialects/test_mysql.py
index fd6b36f1b..9e5b74e0b 100644
--- a/tests/dialects/test_mysql.py
+++ b/tests/dialects/test_mysql.py
@@ -118,6 +118,13 @@ def test_ddl(self):
             "CREATE TABLE `foo` (a VARCHAR(10), INDEX idx_a (a DESC))",
         )
 
+        self.validate_all(
+            "insert into t(i) values (default)",
+            write={
+                "duckdb": "INSERT INTO t (i) VALUES (DEFAULT)",
+                "mysql": "INSERT INTO t (i) VALUES (DEFAULT)",
+            },
+        )
         self.validate_all(
             "CREATE TABLE t (id INT UNSIGNED)",
             write={