add demo instantiation

app.py

@@ -47,7 +47,7 @@ def query_sql(user_query):
     return sql_engine(user_query)
 
 # Define Gradio interface
-iface = gr.Interface(
+demo = gr.Interface(
     fn=query_sql,
     inputs=gr.Textbox(label="Enter your SQL Query"),
     outputs=gr.Textbox(label="Query Result"),
@@ -58,4 +58,4 @@ iface = gr.Interface(
 
 # Launch the app
 if __name__ == "__main__":
-    launch(server_name="0.0.0.0", server_port=7860, share=True)
+    demo.launch(server_name="0.0.0.0", server_port=7860, share=True)