# Page Not Found

The URL `exercise-10-1127.user-purchase-platform` does not exist. This page may have been moved, renamed, or deleted.

## Suggested Pages

You may be looking for one of the following:
- [7.好用的CASE與WHEN IF](https://chiu-kuohsin.gitbook.io/hivesqlbook/part-iii-shu-ju-yu-chu-li-pian/7.-hao-yong-de-case-yu-when-if.md)
- [Part III Intro](https://chiu-kuohsin.gitbook.io/hivesqlbook/part-iii-shu-ju-yu-chu-li-pian/part-iii-intro.md)
- [CASE WHEN函數](https://chiu-kuohsin.gitbook.io/hivesqlbook/part-iii-shu-ju-yu-chu-li-pian/7.-hao-yong-de-case-yu-when-if/case-when-han-shu.md)
- [15.庫、表的操作](https://chiu-kuohsin.gitbook.io/hivesqlbook/part-iv-shu-ju-fen-xi-jin-jie/15.-ku-biao-de-cao-zuo.md)
- [9.煩人的缺失數據與極端值](https://chiu-kuohsin.gitbook.io/hivesqlbook/part-iii-shu-ju-yu-chu-li-pian/9.-fan-ren-de-que-shi-shu-ju-yu-ji-duan-zhi.md)

## How to find the correct page

If the exact page cannot be found, you can still retrieve the information using the documentation query interface.

### Option 1 — Ask a question (recommended)

Perform an HTTP GET request on the documentation index with the `ask` parameter:

```
GET https://chiu-kuohsin.gitbook.io/hivesqlbook/part-iii-shu-ju-yu-chu-li-pian/7.-hao-yong-de-case-yu-when-if.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

### Option 2 — Browse the documentation index

Full index: https://chiu-kuohsin.gitbook.io/hivesqlbook/sitemap.md

Use this to discover valid page paths or navigate the documentation structure.

### Option 3 — Retrieve the full documentation corpus

Full export: https://chiu-kuohsin.gitbook.io/hivesqlbook/llms-full.txt

Use this to access all content at once and perform your own parsing or retrieval. It will be more expensive.

## Tips for requesting documentation

Prefer `.md` URLs for structured content, append `.md` to URLs (e.g., `/hivesqlbook/part-iii-shu-ju-yu-chu-li-pian/7.-hao-yong-de-case-yu-when-if.md`).

You may also use `Accept: text/markdown` header for content negotiation.