-
Notifications
You must be signed in to change notification settings - Fork 1
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
- Loading branch information
Showing
4 changed files
with
171 additions
and
6 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Original file line number | Diff line number | Diff line change |
---|---|---|
@@ -0,0 +1,44 @@ | ||
# User Defined Funtions | ||
|
||
PostgreSQL 提供了四种函数: | ||
|
||
- | ||
|
||
- | ||
|
||
- 内部函数 | ||
|
||
- C语言函数 | ||
|
||
|
||
|
||
|
||
|
||
|
||
## 存储过程-User-Defined Procedures | ||
|
||
存储过程是与函数很相似的数据对象,区别之处在于: | ||
|
||
- | ||
|
||
- 存储过程没有返回值,因此 `CREATE PROCEDURE` 其中没有 `RETURN` 子句 | ||
|
||
- | ||
|
||
|
||
|
||
|
||
|
||
## 查询语句函数-Query Language (SQL) Functions | ||
|
||
```SQL | ||
CREATE FUNCTION clean_emp() RETURNS void AS ' | ||
DELETE FROM emp | ||
WHERE salary < 0; | ||
' LANGUAGE SQL; | ||
|
||
SELECT clean_emp(); | ||
|
||
clean_emp | ||
----------- | ||
``` |