如何进行查询验证

先决条件

本指南假设您熟悉以下内容

在 SQL 数据上进行问答

也许任何 SQL 链或代理中最容易出错的部分是编写有效且安全的 SQL 查询。在本指南中，我们将介绍一些验证查询和处理无效查询的策略。

设置

首先，获取所需的包并设置环境变量

提示

npm install @langchain/community @langchain/openai typeorm sqlite3

export OPENAI_API_KEY="your api key"
# Uncomment the below to use LangSmith. Not required.
# export LANGCHAIN_API_KEY="your api key"
# export LANGCHAIN_TRACING_V2=true

# Reduce tracing latency if you are not in a serverless environment
# export LANGCHAIN_CALLBACKS_BACKGROUND=true

以下示例将使用带 Chinook 数据库的 SQLite 连接。按照这些安装步骤，在与本笔记本相同的目录中创建 Chinook.db

将此文件保存为 Chinook_Sqlite.sql
运行 sqlite3 Chinook.db
运行 .read Chinook_Sqlite.sql
测试 SELECT * FROM Artist LIMIT 10;

现在，Chinhook.db 位于我们的目录中，我们可以使用基于 Typeorm 的 SqlDatabase 类与它交互

import { SqlDatabase } from "langchain/sql_db";
import { DataSource } from "typeorm";

const datasource = new DataSource({
  type: "sqlite",
  database: "../../../../Chinook.db",
});
const db = await SqlDatabase.fromDataSourceParams({
  appDataSource: datasource,
});
console.log(db.allTables.map((t) => t.tableName));
/**
[
  'Album',       'Artist',
  'Customer',    'Employee',
  'Genre',       'Invoice',
  'InvoiceLine', 'MediaType',
  'Playlist',    'PlaylistTrack',
  'Track'
]
 */

API 参考

SqlDatabase 来自 langchain/sql_db

查询检查器

也许最简单的策略是让模型本身检查原始查询中是否存在常见的错误。假设我们有以下 SQL 查询链

import { StringOutputParser } from "@langchain/core/output_parsers";
import { ChatPromptTemplate, PromptTemplate } from "@langchain/core/prompts";
import { RunnableSequence } from "@langchain/core/runnables";
import { ChatOpenAI } from "@langchain/openai";
import { createSqlQueryChain } from "langchain/chains/sql_db";
import { SqlDatabase } from "langchain/sql_db";
import { DataSource } from "typeorm";

const datasource = new DataSource({
  type: "sqlite",
  database: "../../../../Chinook.db",
});
const db = await SqlDatabase.fromDataSourceParams({
  appDataSource: datasource,
});

const llm = new ChatOpenAI({ model: "gpt-4", temperature: 0 });
const chain = await createSqlQueryChain({
  llm,
  db,
  dialect: "sqlite",
});

/**
 * And we want to validate its outputs. We can do so by extending the chain with a second prompt and model call:
 */

const SYSTEM_PROMPT = `Double check the user's {dialect} query for common mistakes, including:
- Using NOT IN with NULL values
- Using UNION when UNION ALL should have been used
- Using BETWEEN for exclusive ranges
- Data type mismatch in predicates
- Properly quoting identifiers
- Using the correct number of arguments for functions
- Casting to the correct data type
- Using the proper columns for joins

If there are any of the above mistakes, rewrite the query. If there are no mistakes, just reproduce the original query.

Output the final SQL query only.`;

const prompt = await ChatPromptTemplate.fromMessages([
  ["system", SYSTEM_PROMPT],
  ["human", "{query}"],
]).partial({ dialect: "sqlite" });

const validationChain = prompt.pipe(llm).pipe(new StringOutputParser());

const fullChain = RunnableSequence.from([
  {
    query: async (i: { question: string }) => chain.invoke(i),
  },
  validationChain,
]);
const query = await fullChain.invoke({
  question:
    "What's the average Invoice from an American customer whose Fax is missing since 2003 but before 2010",
});
console.log("query", query);
/**
query SELECT AVG("Total") FROM "Invoice" WHERE "CustomerId" IN (SELECT "CustomerId" FROM "Customer" WHERE "Country" = 'USA' AND "Fax" IS NULL) AND "InvoiceDate" BETWEEN '2003-01-01 00:00:00' AND '2009-12-31 23:59:59'
 */
console.log("db query results", await db.run(query));
/**
db query results [{"AVG(\"Total\")":6.632999999999998}]
 */

// -------------

// You can see a LangSmith trace of the above chain here:
// https://smith.langchain.com/public/d1131395-8477-47cd-8f74-e0c5491ea956/r

// -------------

// The obvious downside of this approach is that we need to make two model calls instead of one to generate our query.
// To get around this we can try to perform the query generation and query check in a single model invocation:

const SYSTEM_PROMPT_2 = `You are a {dialect} expert. Given an input question, create a syntactically correct {dialect} query to run.
Unless the user specifies in the question a specific number of examples to obtain, query for at most {top_k} results using the LIMIT clause as per {dialect}. You can order the results to return the most informative data in the database.
Never query for all columns from a table. You must query only the columns that are needed to answer the question. Wrap each column name in double quotes (") to denote them as delimited identifiers.
Pay attention to use only the column names you can see in the tables below. Be careful to not query for columns that do not exist. Also, pay attention to which column is in which table.
Pay attention to use date('now') function to get the current date, if the question involves "today".

Only use the following tables:
{table_info}

Write an initial draft of the query. Then double check the {dialect} query for common mistakes, including:
- Using NOT IN with NULL values
- Using UNION when UNION ALL should have been used
- Using BETWEEN for exclusive ranges
- Data type mismatch in predicates
- Properly quoting identifiers
- Using the correct number of arguments for functions
- Casting to the correct data type
- Using the proper columns for joins

Use format:

First draft: <<FIRST_DRAFT_QUERY>>
Final answer: <<FINAL_ANSWER_QUERY>>`;

const prompt2 = await PromptTemplate.fromTemplate(
  `System: ${SYSTEM_PROMPT_2}

Human: {input}`
).partial({ dialect: "sqlite" });

const parseFinalAnswer = (output: string): string =>
  output.split("Final answer: ")[1];

const chain2 = (
  await createSqlQueryChain({
    llm,
    db,
    prompt: prompt2,
    dialect: "sqlite",
  })
).pipe(parseFinalAnswer);

const query2 = await chain2.invoke({
  question:
    "What's the average Invoice from an American customer whose Fax is missing since 2003 but before 2010",
});
console.log("query2", query2);
/**
query2 SELECT AVG("Total") FROM "Invoice" WHERE "CustomerId" IN (SELECT "CustomerId" FROM "Customer" WHERE "Country" = 'USA' AND "Fax" IS NULL) AND date("InvoiceDate") BETWEEN date('2003-01-01') AND date('2009-12-31') LIMIT 5
 */
console.log("db query results", await db.run(query2));

/**
db query results [{"AVG(\"Total\")":6.632999999999998}]
 */

// -------------

// You can see a LangSmith trace of the above chain here:
// https://smith.langchain.com/public/e21d6146-eca9-4de6-a078-808fd09979ea/r

// -------------

API 参考

StringOutputParser 来自 @langchain/core/output_parsers
ChatPromptTemplate 来自 @langchain/core/prompts
PromptTemplate 来自 @langchain/core/prompts
RunnableSequence 来自 @langchain/core/runnables
ChatOpenAI 来自 @langchain/openai
createSqlQueryChain 来自 langchain/chains/sql_db
SqlDatabase 来自 langchain/sql_db

下一步

您现在已经了解了一些验证生成的 SQL 查询的策略。

接下来，查看本节中的其他一些指南，例如如何在大型数据库上进行查询.

如何进行查询验证

设置

API 参考

查询检查器

API 参考

下一步

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您也可以留下详细的反馈在 GitHub 上.

如何进行查询验证

设置​

API 参考

查询检查器​

API 参考

下一步​

此页面是否有帮助？

您也可以留下详细的反馈 在 GitHub 上.

设置

查询检查器

下一步

您也可以留下详细的反馈在 GitHub 上.