fix(db2): do not embed inline COMMENT= in CTAS SQL

Db2 rejects COMMENT= as a table property in CREATE TABLE ... AS ... WITH DATA
statements (SQL0104N). The CTAS path in _create_table was passing table_description
into _build_create_table_exp which unconditionally injects a SchemaCommentProperty.

Fix: pass table_description=None to _build_create_table_exp on the CTAS path.
The description is still applied correctly via a separate COMMENT ON TABLE command
(COMMENT_CREATION_TABLE = COMMENT_COMMAND_ONLY already handles this at line 462).

Fixes: test_ctas_source_columns[db2] CI failure.
Adds: test_ctas_with_table_description unit test to prevent regression.

Author: iawanish

sqlmesh/core/engine_adapter/db2.py

@@ -432,13 +432,17 @@ def _create_table(
             else:
                 self.drop_view(table, ignore_if_not_exists=True)
 
+            # Do NOT pass table_description here: Db2 does not support inline
+            # COMMENT= in CREATE TABLE AS ... WITH DATA syntax (SQL0104N).
+            # The description is applied via a separate COMMENT ON TABLE command
+            # below (when COMMENT_CREATION_TABLE.is_comment_command_only).
             create_exp = self._build_create_table_exp(
                 table_name_or_schema=table_name_or_schema,
                 expression=expression,
                 exists=False,
                 replace=False,
                 target_columns_to_types=target_columns_to_types,
-                table_description=table_description,
+                table_description=None,
                 table_kind=table_kind,
                 **kwargs,
             )

tests/core/engine_adapter/test_db2.py

@@ -221,6 +221,38 @@ def test_ctas_with_data(adapter: Db2EngineAdapter, mocker: MockerFixture):
     assert "_subquery" not in sql_calls[0]
 
 
+def test_ctas_with_table_description(adapter: Db2EngineAdapter, mocker: MockerFixture):
+    """CTAS with table_description must not embed COMMENT= in the CREATE TABLE SQL.
+
+    Db2 rejects inline COMMENT= in CTAS (SQL0104N).  The description must be
+    applied via a separate COMMENT ON TABLE statement after the table is created.
+    """
+    mocker.patch.object(adapter, "table_exists", return_value=False)
+    mocker.patch.object(adapter, "drop_view")
+
+    adapter.ctas(
+        table_name="test_schema.test_table",
+        query_or_df=parse_one("SELECT id FROM source_table"),
+        exists=False,
+        table_description="test table description",
+        column_descriptions={"id": "test id column description"},
+    )
+
+    sql_calls = to_sql_calls(adapter)
+    # First call: the CTAS itself — must contain WITH DATA and no inline COMMENT=
+    assert "CREATE TABLE" in sql_calls[0]
+    assert "WITH DATA" in sql_calls[0]
+    assert "COMMENT=" not in sql_calls[0].replace(" ", "")
+    # Second call: separate COMMENT ON TABLE
+    assert any("COMMENT ON TABLE" in c for c in sql_calls), (
+        "Expected a separate COMMENT ON TABLE statement"
+    )
+    # Third call: separate COMMENT ON COLUMN
+    assert any("COMMENT ON COLUMN" in c for c in sql_calls), (
+        "Expected a separate COMMENT ON COLUMN statement"
+    )
+
+
 # ---------------------------------------------------------------------------
 # drop_view — guards via SYSCAT.VIEWS (no DROP VIEW IF EXISTS in Db2)
 # ---------------------------------------------------------------------------