fix: Database reserved keyword issue

The fix will use quotes to escape "key", which is column name in the metadata table. Should work for different database types.

Merge https://github.com/google/adk-python/pull/4106

COPYBARA_INTEGRATE_REVIEW=https://github.com/google/adk-python/pull/4106 from DineshThumma9:fix/mysql-reserved-keyword-issue e39d0d02f3695d6890bc3267417b5dad58f7e8ee
PiperOrigin-RevId: 854411915

src/google/adk/sessions/migration/_schema_check_utils.py

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 """Database schema version check utility."""
+
 from __future__ import annotations
 
 import logging
@@ -32,8 +33,11 @@ def _get_schema_version_impl(inspector, connection) -> str:
   """Gets DB schema version using inspector and connection."""
   if inspector.has_table("adk_internal_metadata"):
     try:
+      key_col = inspector.dialect.identifier_preparer.quote("key")
       result = connection.execute(
-          text("SELECT value FROM adk_internal_metadata WHERE key = :key"),
+          text(
+              f"SELECT value FROM adk_internal_metadata WHERE {key_col} = :key"
+          ),
           {"key": SCHEMA_VERSION_KEY},
       ).fetchone()
       if result:
@@ -49,6 +53,7 @@ def _get_schema_version_impl(inspector, connection) -> str:
           e,
       )
       raise
+
   # Metadata table doesn't exist, check for v0 schema.
   # V0 schema has an 'events' table with an 'actions' column.
   if inspector.has_table("events"):

tests/unittests/sessions/migration/test_database_schema.py

@@ -51,12 +51,18 @@ async def test_new_db_uses_latest_schema(tmp_path):
         lambda sync_conn: inspect(sync_conn).has_table('adk_internal_metadata')
     )
     assert has_metadata_table
-    schema_version = await conn.run_sync(
-        lambda sync_conn: sync_conn.execute(
-            text('SELECT value FROM adk_internal_metadata WHERE key = :key'),
-            {'key': _schema_check_utils.SCHEMA_VERSION_KEY},
-        ).scalar_one_or_none()
-    )
+
+    def get_schema_version(sync_conn):
+      inspector = inspect(sync_conn)
+      key_col = inspector.dialect.identifier_preparer.quote('key')
+      return sync_conn.execute(
+          text(
+              f'SELECT value FROM adk_internal_metadata WHERE {key_col} = :key'
+          ),
+          {'key': _schema_check_utils.SCHEMA_VERSION_KEY},
+      ).scalar_one_or_none()
+
+    schema_version = await conn.run_sync(get_schema_version)
     assert schema_version == _schema_check_utils.LATEST_SCHEMA_VERSION
 
     # Verify events table columns for v1