change prompt a little

llm.py

@@ -43,7 +43,7 @@ def generate_system_prompt(table_name, table_schema):
         column_type = col[2]
         prompt += f"- {column_name} ({column_type})\n"
 
-    prompt += "\nPlease generate a SQL query based on the following natural language question. ONLY return the SQL query."
+    prompt += "\nGenerate a SQL query based on the following natural language question. ONLY return the SQL query and nothing else."
 
     return prompt