# 4. SQL 語法

這章中說明 SQL 的使用語法。從這裡建立後續章節所需的理解基礎，然後進一步瞭解 SQL 如何使用去定義及修改資料。

我們也建議已經熟悉 SQL 語法的使用者，仔細地閱讀本章，因為這裡包含了一些有別於其他 SQL 資料庫或專屬於 PostgreSQL 的規則和觀念。


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