使用 JavaScript 和 PostgreSQL 查询数据库

JavaScript

PostgreSQL

使用 Prisma 客户端编写你的第一个查询

¥Write your first query with Prisma Client

现在你已经生成了 Prisma 客户端，你可以开始编写查询以在数据库中读取和写入数据。出于本指南的目的，你将使用简单的 Node.js 脚本来探索 Prisma Client 的一些基本功能。

¥Now that you have generated Prisma Client, you can start writing queries to read and write data in your database. For the purpose of this guide, you'll use a plain Node.js script to explore some basic features of Prisma Client.

创建一个名为 index.js 的新文件并添加以下代码：

¥Create a new file named index.js and add the following code to it:

index.js

const { PrismaClient } = require('./generated/prisma')

const prisma = new PrismaClient()

async function main() {
  // ... you will write your Prisma Client queries here
}

main()
  .then(async () => {
    await prisma.$disconnect()
  })
  .catch(async (e) => {
    console.error(e)
    await prisma.$disconnect()
    process.exit(1)
  })

以下是代码片段不同部分的快速概述：

¥Here's a quick overview of the different parts of the code snippet:

1. 从 prisma init 命令中指定的 output 目录导入 PrismaClient。

   ¥Import PrismaClient from the output directory specified in the prisma init command.

2. 实例化 PrismaClient

   ¥Instantiate PrismaClient

3. 定义一个名为 main 的 async 函数来向数据库发送查询

   ¥Define an async function named main to send queries to the database

4. 调用 main 函数

   ¥Call the main function

5. 脚本终止时关闭数据库连接

   ¥Close the database connections when the script terminates

在 main 函数中，添加以下查询以从数据库读取所有 User 记录并打印结果：

¥Inside the main function, add the following query to read all User records from the database and print the result:

index.js

async function main() {
  // ... you will write your Prisma Client queries here
  const allUsers = await prisma.user.findMany()
  console.log(allUsers)
}

现在使用以下命令运行代码：

¥Now run the code with this command:

node index.js

这应该打印一个空数组，因为数据库中还没有 User 记录：

¥This should print an empty array because there are no User records in the database yet:

[]

将数据写入数据库

¥Write data into the database

你在上一节中使用的 findMany 查询仅从数据库中读取数据（尽管它仍然是空的）。在本节中，你将学习如何编写查询以将新记录写入 Post 和 User 表中。

¥The findMany query you used in the previous section only reads data from the database (although it was still empty). In this section, you'll learn how to write a query to write new records into the Post and User tables.

调整 main 函数以向数据库发送 create 查询：

¥Adjust the main function to send a create query to the database:

index.js

async function main() {
  await prisma.user.create({
    data: {
      name: 'Alice',
      email: 'alice@prisma.io',
      posts: {
        create: { title: 'Hello World' },
      },
      profile: {
        create: { bio: 'I like turtles' },
      },
    },
  })

  const allUsers = await prisma.user.findMany({
    include: {
      posts: true,
      profile: true,
    },
  })
  console.dir(allUsers, { depth: null })
}

此代码使用 嵌套写入 查询创建新的 User 记录以及新的 Post 和 Profile 记录。User 记录分别通过 Post.author ↔ User.posts 和 Profile.user ↔ User.profile 关系字段 连接到另外两个记录。

¥This code creates a new User record together with new Post and Profile records using a nested write query. The User record is connected to the two other ones via the Post.author ↔ User.posts and Profile.user ↔ User.profile relation fields respectively.

请注意，你将 include 选项传递给 findMany，这告诉 Prisma 客户端在返回的 User 对象上包含 posts 和 profile 关系。

¥Notice that you're passing the include option to findMany which tells Prisma Client to include the posts and profile relations on the returned User objects.

使用以下命令运行代码：

¥Run the code with this command:

node index.js

输出应类似于以下内容：

¥The output should look similar to this:

[
  {
    email: 'alice@prisma.io',
    id: 1,
    name: 'Alice',
    posts: [
      {
        content: null,
        createdAt: 2020-03-21T16:45:01.246Z,
        updatedAt: 2020-03-21T16:45:01.246Z,
        id: 1,
        published: false,
        title: 'Hello World',
        authorId: 1,
      }
    ],
    profile: {
      bio: 'I like turtles',
      id: 1,
      userId: 1,
    }
  }
]

该查询将新记录添加到 User 和 Post 表中：

¥The query added new records to the User and the Post tables:

用户

¥User

id	email	name
1	"alice@prisma.io"	"Alice"

邮政

¥Post

id	createdAt	updatedAt	title	content	published	authorId
1	2020-03-21T16:45:01.246Z	2020-03-21T16:45:01.246Z	"Hello World"	null	false	1

轮廓

¥Profile

id	bio	userId
1	"I like turtles"	1

注意：Post 上的 authorId 列和 Profile 上的 userId 列中的数字都引用 User 表的 id 列，这意味着 id 值 1 列因此引用数据库中的第一条（也是唯一一条）User 记录。

¥Note: The numbers in the authorId column on Post and userId column on Profile both reference the id column of the User table, meaning the id value 1 column therefore refers to the first (and only) User record in the database.

在继续下一部分之前，你需要对刚刚使用 update 查询创建的 Post 记录进行 "publish" 操作。调整 main 功能如下：

¥Before moving on to the next section, you'll "publish" the Post record you just created using an update query. Adjust the main function as follows:

index.js

async function main() {
  const post = await prisma.post.update({
    where: { id: 1 },
    data: { published: true },
  })
  console.log(post)
}

现在使用与之前相同的命令运行代码：

¥Now run the code using the same command as before:

node index.js

你将看到以下输出：

¥You will see the following output:

{
  id: 1,
  title: 'Hello World',
  content: null,
  published: true,
  authorId: 1
}

id 为 1 的 Post 记录现已在数据库中更新：

¥The Post record with an id of 1 now got updated in the database:

邮政

¥Post

id	title	content	published	authorId
1	"Hello World"	null	true	1

太棒了，你刚刚使用 Prisma 客户端第一次将新数据写入数据库 🚀

¥Fantastic, you just wrote new data into your database for the first time using Prisma Client 🚀