add few shot example (#148)

langchain/chains/sql_database/prompt.py

@@ -1,5 +1,5 @@
 # flake8: noqa
-from langchain.prompts.prompt import Prompt
+from langchain.prompts.prompt import PromptTemplate
 
 _DEFAULT_TEMPLATE = """Given an input question, first create a syntactically correct {dialect} query to run, then look at the results of the query and return the answer.
 Use the following format:
@@ -14,6 +14,6 @@ Only use the following tables:
 {table_info}
 
 Question: {input}"""
-PROMPT = Prompt(
+PROMPT = PromptTemplate(
     input_variables=["input", "table_info", "dialect"], template=_DEFAULT_TEMPLATE
 )