diff --git a/backend/apps/datasource/crud/datasource.py b/backend/apps/datasource/crud/datasource.py
index fc502f0f9..3a35fd478 100644
--- a/backend/apps/datasource/crud/datasource.py
+++ b/backend/apps/datasource/crud/datasource.py
@@ -392,45 +392,48 @@ def get_table_schema(session: SessionDep, current_user: CurrentUser, ds: CoreDat
     # field relation
     if tables and ds.table_relation:
         relations = list(filter(lambda x: x.get('shape') == 'edge', ds.table_relation))
-        # Complete the missing table
-        # get tables in relation, remove irrelevant relation
-        embedding_table_ids = [s.get('id') for s in tables]
-        all_relations = list(filter(lambda x: x.get('source').get('cell') in embedding_table_ids or x.get('target').get(
-            'cell') in embedding_table_ids, relations))
-
-        # get relation table ids, sub embedding table ids
-        relation_table_ids = []
-        for r in all_relations:
-            relation_table_ids.append(r.get('source').get('cell'))
-            relation_table_ids.append(r.get('target').get('cell'))
-        relation_table_ids = list(set(relation_table_ids))
-        # get table dict
-        table_records = session.query(CoreTable).filter(CoreTable.id.in_(list(map(int, relation_table_ids)))).all()
-        table_dict = {}
-        for ele in table_records:
-            table_dict[ele.id] = ele.table_name
-
-        # get lost table ids
-        lost_table_ids = list(set(relation_table_ids) - set(embedding_table_ids))
-        # get lost table schema and splice it
-        lost_tables = list(filter(lambda x: x.get('id') in lost_table_ids, all_tables))
-        if lost_tables:
-            for s in lost_tables:
-                schema_str += s.get('schema_table')
-
-        # get field dict
-        relation_field_ids = []
-        for relation in all_relations:
-            relation_field_ids.append(relation.get('source').get('port'))
-            relation_field_ids.append(relation.get('target').get('port'))
-        relation_field_ids = list(set(relation_field_ids))
-        field_records = session.query(CoreField).filter(CoreField.id.in_(list(map(int, relation_field_ids)))).all()
-        field_dict = {}
-        for ele in field_records:
-            field_dict[ele.id] = ele.field_name
-
-        schema_str += '【Foreign keys】\n'
-        for ele in all_relations:
-            schema_str += f"{table_dict.get(int(ele.get('source').get('cell')))}.{field_dict.get(int(ele.get('source').get('port')))}={table_dict.get(int(ele.get('target').get('cell')))}.{field_dict.get(int(ele.get('target').get('port')))}\n"
+        if relations:
+            # Complete the missing table
+            # get tables in relation, remove irrelevant relation
+            embedding_table_ids = [s.get('id') for s in tables]
+            all_relations = list(
+                filter(lambda x: x.get('source').get('cell') in embedding_table_ids or x.get('target').get(
+                    'cell') in embedding_table_ids, relations))
+
+            # get relation table ids, sub embedding table ids
+            relation_table_ids = []
+            for r in all_relations:
+                relation_table_ids.append(r.get('source').get('cell'))
+                relation_table_ids.append(r.get('target').get('cell'))
+            relation_table_ids = list(set(relation_table_ids))
+            # get table dict
+            table_records = session.query(CoreTable).filter(CoreTable.id.in_(list(map(int, relation_table_ids)))).all()
+            table_dict = {}
+            for ele in table_records:
+                table_dict[ele.id] = ele.table_name
+
+            # get lost table ids
+            lost_table_ids = list(set(relation_table_ids) - set(embedding_table_ids))
+            # get lost table schema and splice it
+            lost_tables = list(filter(lambda x: x.get('id') in lost_table_ids, all_tables))
+            if lost_tables:
+                for s in lost_tables:
+                    schema_str += s.get('schema_table')
+
+            # get field dict
+            relation_field_ids = []
+            for relation in all_relations:
+                relation_field_ids.append(relation.get('source').get('port'))
+                relation_field_ids.append(relation.get('target').get('port'))
+            relation_field_ids = list(set(relation_field_ids))
+            field_records = session.query(CoreField).filter(CoreField.id.in_(list(map(int, relation_field_ids)))).all()
+            field_dict = {}
+            for ele in field_records:
+                field_dict[ele.id] = ele.field_name
+
+            if all_relations:
+                schema_str += '【Foreign keys】\n'
+                for ele in all_relations:
+                    schema_str += f"{table_dict.get(int(ele.get('source').get('cell')))}.{field_dict.get(int(ele.get('source').get('port')))}={table_dict.get(int(ele.get('target').get('cell')))}.{field_dict.get(int(ele.get('target').get('port')))}\n"
 
     return schema_str