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GitHub Repository: huggingface/notebooks
 Path: blob/main/smolagents_doc/zh/text_to_sql.ipynb
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Kernel: Unknown Kernel
# Installation
! pip install smolagents
# To install from source instead of the last release, comment the command above and uncomment the following one.
# ! pip install git+https://github.com/huggingface/smolagents.git

Text-to-SQL

在此教程中，我们将看到如何使用 smolagents 实现一个利用 SQL 的 agent。

让我们从经典问题开始：为什么不简单地使用标准的 text-to-SQL pipeline 呢？

标准的 text-to-SQL pipeline 很脆弱，因为生成的 SQL 查询可能会出错。更糟糕的是，查询可能出错却不引发错误警报，从而返回一些不正确或无用的结果。

👉 相反，agent 系统则可以检视输出结果并决定查询是否需要被更改，因此带来巨大的性能提升。

让我们来一起构建这个 agent! 💪

首先，我们构建一个 SQL 的环境：

from sqlalchemy import (
    create_engine,
    MetaData,
    Table,
    Column,
    String,
    Integer,
    Float,
    insert,
    inspect,
    text,
)

engine = create_engine("sqlite:///:memory:")
metadata_obj = MetaData()

# create city SQL table
table_name = "receipts"
receipts = Table(
    table_name,
    metadata_obj,
    Column("receipt_id", Integer, primary_key=True),
    Column("customer_name", String(16), primary_key=True),
    Column("price", Float),
    Column("tip", Float),
)
metadata_obj.create_all(engine)

rows = [
    {"receipt_id": 1, "customer_name": "Alan Payne", "price": 12.06, "tip": 1.20},
    {"receipt_id": 2, "customer_name": "Alex Mason", "price": 23.86, "tip": 0.24},
    {"receipt_id": 3, "customer_name": "Woodrow Wilson", "price": 53.43, "tip": 5.43},
    {"receipt_id": 4, "customer_name": "Margaret James", "price": 21.11, "tip": 1.00},
]
for row in rows:
    stmt = insert(receipts).values(**row)
    with engine.begin() as connection:
        cursor = connection.execute(stmt)

构建 agent

现在，我们构建一个 agent，它将使用 SQL 查询来回答问题。工具的 description 属性将被 agent 系统嵌入到 LLM 的提示中：它为 LLM 提供有关如何使用该工具的信息。这正是我们描述 SQL 表的地方。

inspector = inspect(engine)
columns_info = [(col["name"], col["type"]) for col in inspector.get_columns("receipts")]

table_description = "Columns:\n" + "\n".join([f"  - {name}: {col_type}" for name, col_type in columns_info])
print(table_description)

Columns:
  - receipt_id: INTEGER
  - customer_name: VARCHAR(16)
  - price: FLOAT
  - tip: FLOAT

现在让我们构建我们的工具。它需要以下内容：（更多细节请参阅工具文档）

  • 一个带有 Args: 部分列出参数的 docstring。

  • 输入和输出的type hints。

from smolagents import tool

@tool
def sql_engine(query: str) -> str:
    """
    Allows you to perform SQL queries on the table. Returns a string representation of the result.
    The table is named 'receipts'. Its description is as follows:
        Columns:
        - receipt_id: INTEGER
        - customer_name: VARCHAR(16)
        - price: FLOAT
        - tip: FLOAT

    Args:
        query: The query to perform. This should be correct SQL.
    """
    output = ""
    with engine.connect() as con:
        rows = con.execute(text(query))
        for row in rows:
            output += "\n" + str(row)
    return output

我们现在使用这个工具来创建一个 agent。我们使用 CodeAgent，这是 smolagent 的主要 agent 类：一个在代码中编写操作并根据 ReAct 框架迭代先前输出的 agent。

这个模型是驱动 agent 系统的 LLM。InferenceClientModel 允许你使用 HF Inference API 调用 LLM，无论是通过 Serverless 还是 Dedicated endpoint，但你也可以使用任何专有 API。

from smolagents import CodeAgent, InferenceClientModel

agent = CodeAgent(
    tools=[sql_engine],
    model=InferenceClientModel(model_id="meta-llama/Meta-Llama-3.1-8B-Instruct"),
)
agent.run("Can you give me the name of the client who got the most expensive receipt?")

Level 2: 表连接

现在让我们增加一些挑战！我们希望我们的 agent 能够处理跨多个表的连接。因此，我们创建一个新表，记录每个 receipt_id 的服务员名字！

table_name = "waiters"
receipts = Table(
    table_name,
    metadata_obj,
    Column("receipt_id", Integer, primary_key=True),
    Column("waiter_name", String(16), primary_key=True),
)
metadata_obj.create_all(engine)

rows = [
    {"receipt_id": 1, "waiter_name": "Corey Johnson"},
    {"receipt_id": 2, "waiter_name": "Michael Watts"},
    {"receipt_id": 3, "waiter_name": "Michael Watts"},
    {"receipt_id": 4, "waiter_name": "Margaret James"},
]
for row in rows:
    stmt = insert(receipts).values(**row)
    with engine.begin() as connection:
        cursor = connection.execute(stmt)

因为我们改变了表，我们需要更新 SQLExecutorTool，让 LLM 能够正确利用这个表的信息。

updated_description = """Allows you to perform SQL queries on the table. Beware that this tool's output is a string representation of the execution output.
It can use the following tables:"""

inspector = inspect(engine)
for table in ["receipts", "waiters"]:
    columns_info = [(col["name"], col["type"]) for col in inspector.get_columns(table)]

    table_description = f"Table '{table}':\n"

    table_description += "Columns:\n" + "\n".join([f"  - {name}: {col_type}" for name, col_type in columns_info])
    updated_description += "\n\n" + table_description

print(updated_description)

因为这个request 比之前的要难一些，我们将 LLM 引擎切换到更强大的 Qwen/Qwen2.5-Coder-32B-Instruct！

sql_engine.description = updated_description

agent = CodeAgent(
    tools=[sql_engine],
    model=InferenceClientModel(model_id="Qwen/Qwen2.5-Coder-32B-Instruct"),
)

agent.run("Which waiter got more total money from tips?")

它直接就能工作！设置过程非常简单，难道不是吗？

这个例子到此结束！我们涵盖了这些概念：

  • 构建新工具。

  • 更新工具的描述。

  • 切换到更强大的 LLM 有助于 agent 推理。

✅ 现在你可以构建你一直梦寐以求的 text-to-SQL 系统了！✨