# 2. SQL 查詢語言

本章適合初學資料庫的朋友閱讀，以簡單的語法範例，實際操作以瞭解資料庫的運作方式。事實上，更複雜的資料庫行為，也不脫這個基本的操作模式。


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.postgresql.tw/14/tutorial/the-sql-language.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.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.