# 38. SQL 延伸功能

在接下來的部分中，我們將討論如何透過增加以下內容來延伸 PostgreSQL 中 SQL 查詢語言的功能：

* functions (從[第 38.3 節](/16/server-programming/extending-sql/user-defined-functions.md)開始)
* aggregates (從[第 38.12 節](/16/server-programming/extending-sql/user-defined-aggregates.md)開始)
* data types (從[第 38.13 節](/16/server-programming/extending-sql/user-defined-types.md)開始)
* operators (從[第 38.14 節](/16/server-programming/extending-sql/user-defined-operators.md)開始)
* operator classes for indexes (從[第 38.16 節](/16/server-programming/extending-sql/interfacing-extensions-to-indexes.md)開始)
* packages of related objects (從[第 38.17 節](/16/server-programming/extending-sql/packaging-related-objects-into-an-extension.md)開始)


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