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SqlDatabaseChain 中文：Sql数据库链

SqlDatabaseChain 可以让您在 SQL 数据库上回答问题。 此示例使用 Chinook 数据库，这是一个可用于 SQL Server、Oracle、MySQL 等的示例数据库。

设置​

首先安装 typeorm ：typeorm包是必须安装的

npm install typeorm

然后安装所需的数据库依赖项。例如，对于 SQLite 

npm install sqlite3

对于其他数据库，请参阅 https://typeorm.io/#installation

最后，按照 https://database.guide/2-sample-databases-sqlite/ 上的说明，获取此示例所需的样品数据库。

import { DataSource } from "typeorm";
import { OpenAI } from "langchain/llms/openai";
import { SqlDatabase } from "langchain/sql_db";
import { SqlDatabaseChain } from "langchain/chains";

/**
 * This example uses Chinook database, which is a sample database available for SQL Server, Oracle, MySQL, etc.
 * To set it up follow the instructions on https://database.guide/2-sample-databases-sqlite/, placing the .db file
 * in the examples folder.
 */
const datasource = new DataSource({
  type: "sqlite",
  database: "Chinook.db",
});

const db = await SqlDatabase.fromDataSourceParams({
  appDataSource: datasource,
});

const chain = new SqlDatabaseChain({
  llm: new OpenAI({ temperature: 0 }),
  database: db,
});

const res = await chain.run("How many tracks are there?");
console.log(res);
// There are 3503 tracks.

您可以在创建 SqlDatabase 对象时包含或排除表格，以帮助链集中于您想要的表格。 它还可以减少链中使用的令牌数量。

const db = await SqlDatabase.fromDataSourceParams({

  appDataSource: datasource,

  includesTables: ["Track"],

});

如果需要，您可以在调用链时返回使用的 SQL 命令。

import { DataSource } from "typeorm";
import { OpenAI } from "langchain/llms/openai";
import { SqlDatabase } from "langchain/sql_db";
import { SqlDatabaseChain } from "langchain/chains";

/**
 * This example uses Chinook database, which is a sample database available for SQL Server, Oracle, MySQL, etc.
 * To set it up follow the instructions on https://database.guide/2-sample-databases-sqlite/, placing the .db file
 * in the examples folder.
 */
const datasource = new DataSource({
  type: "sqlite",
  database: "Chinook.db",
});

const db = await SqlDatabase.fromDataSourceParams({
  appDataSource: datasource,
});

const chain = new SqlDatabaseChain({
  llm: new OpenAI({ temperature: 0 }),
  database: db,
  sqlOutputKey: "sql",
});

const res = await chain.call({ query: "How many tracks are there?" });
/* Expected result:
 * {
 *   result: ' There are 3503 tracks.',
 *   sql: ' SELECT COUNT(*) FROM "Track";'
 * }
 */
console.log(res);