Exercise 1: The Self-Referencing Schema — Possible Solution
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THE SCHEMA
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// db/schema.ts
import { mysqlTable, int, varchar, text, AnyMySqlColumn } from 'drizzle-orm/mysql-core';

export const pages = mysqlTable('pages', {
  id: int('id').primaryKey().autoincrement(),
  slug: varchar('slug', { length: 255 }).notNull(),
  fullPath: varchar('full_path', { length: 1024 }).notNull().unique(),
  title: varchar('title', { length: 255 }).notNull(),
  body: text('body'),
  parentId: int('parent_id').references(
    (): AnyMySqlColumn => pages.id,
    { onDelete: 'restrict' }
  ),
});

WHY THE FUNCTION-BASED WORKAROUND IS NEEDED
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Per this chapter, references() would normally take a direct reference to another table's column, but pages.id can't be referenced directly from inside the same pages table's own definition - the pages constant doesn't fully exist yet while TypeScript is still evaluating it. Wrapping the reference in an arrow function, (): AnyMySqlColumn => pages.id, defers evaluation until the function is actually called, by which point pages is fully defined.

WHY THIS WORKS AS AN ANSWER
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It correctly defines every column from the chapter's own schema, and correctly explains why the self-referencing foreign key needs a function wrapper rather than a direct column reference.