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sqlmigrate 与检查 SQL

查看迁移将要执行的原始 SQL

sqlmigrate 与检查 SQL 是 CoddyKit 上的免费 Django Academy 课时。这是第 4 节课，共 4 节。你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。这是 Django Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 Django Academy 课程共包含 4 节课。

本课时的部分内容尚未翻译，以英文显示。

See the Real SQL

Migrations are Python, but the database speaks SQL. The sqlmigrate command shows the exact SQL a migration will run.

How to Run It

Give sqlmigrate an app label and a migration number, and it prints the SQL without applying anything.

python manage.py sqlmigrate blog 0002

It Does Not Apply

sqlmigrate is read-only. It prints the statements so you can review them, never touching your database.

Reading CREATE TABLE

An initial migration shows a CREATE TABLE with each column, type, and constraint laid out in plain SQL.

CREATE TABLE "blog_post" (
  "id" integer PRIMARY KEY AUTOINCREMENT,
  "title" varchar(200) NOT NULL
);

Reading ALTER TABLE

Adding a field shows an ALTER TABLE ... ADD COLUMN, the precise change Django will make to the existing table.

ALTER TABLE "blog_post"
  ADD COLUMN "published" bool NOT NULL DEFAULT 0;

Why Inspect First

Previewing SQL catches surprises early, like an unexpected rebuild or a costly change on a huge table.

Dialect Matters

The SQL reflects your configured database. Postgres, SQLite, and MySQL each produce slightly different statements.

Find the Number

Need the migration number? Run showmigrations first to list them, then pass the one you want to sqlmigrate.

python manage.py showmigrations blog

Backwards SQL

Add the --backwards flag to see the SQL Django would run to reverse a migration, useful before rolling back.

python manage.py sqlmigrate blog 0002 --backwards

A Learning Tool

sqlmigrate is a great way to learn how the ORM maps your models to tables, columns, indexes, and constraints.

Review Before Production

On important deploys, read the SQL for risky steps so a slow migration never locks your live tables unexpectedly.

Quick Check

What does python manage.py sqlmigrate do?

Recap

With sqlmigrate you preview the exact SQL behind any migration, forwards or backwards, so deploys hold no surprises. 🔍

常见问题解答

「sqlmigrate 与检查 SQL」课时是免费的吗？

是的 — 「sqlmigrate 与检查 SQL」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 Django Academy 课程的其余内容，请升级到 CoddyKit PRO。 Django Academy 课程共包含 4 节课。

「sqlmigrate 与检查 SQL」这节课中我会学到什么？

查看迁移将要执行的原始 SQL 你通过在浏览器中直接运行的动手代码来练习 Django Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。

学习 Django Academy 需要有经验吗？

无需任何先前经验。CoddyKit 上的 Django Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。这是第 4 节课，共 4 节。

「sqlmigrate 与检查 SQL」课时需要多长时间？

大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。

我能在这节 Django Academy 课中编写并运行代码吗？

能。每节 Django Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。

此课程中的所有课时

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