Step 1: Parse Table Definition

从用户输入的表定义中提取关键信息。

Input Format

Table: products
Fields:
- id (primary key)
- name (string, 100, required)
- category_id (foreign key -> categories)
- description (text, nullable)
- price (decimal 10,2, required)
- stock (integer, default 0)
- status (tinyint, default 1)

输入容错与默认推断