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在 PostgreSQL 中使用函数处理数据

Brian Piccolo

Sr. Director, Digital Strategy

Sakila 数据库

高度规范化
具有代表性的数据类型
自定义函数

主题

PostgreSQL 常用数据类型
日期与时间函数与运算符
解析与处理文本
全文检索与 PostgreSQL 扩展

常见数据类型

文本数据类型
- CHAR、VARCHAR、TEXT
数值数据类型
- INT 与 DECIMAL
日期/时间数据类型
- DATE、TIME、TIMESTAMP、INTERVAL
数组

文本数据类型

SELECT title 
FROM film
LIMIT 5

+-------------------+
| title             |
|-------------------|
| ACADEMY DINOSAUR  |
| ACE GOLDFINGER    |
| ADAPTATION HOLES  |
| AFFAIR PREJUDICE  |
| AFRICAN EGG       |
+-------------------+

SELECT description 
FROM film
LIMIT 2

+-----------------------------------------+
| description                             |
|-----------------------------------------|
| A Epic Drama of a Feminist And a Mad    |     
|  Scientist who must Battle a Teacher in |
|  The Canadian Rockies.                  |
| A Astounding Epistle of a Database      |
|  Administrator And a Explorer who       |
|  must Find a Car in Ancient China       |
+-----------------------------------------+

数值数据类型

SELECT 
    payment_id 
FROM payment 
LIMIT 5

+-------------+
| payment_id  |
|-------------|
| 1           |
| 2           |
| 3           |
| 4           |
| 5           |
+-------------+

SELECT 
    amount
FROM payment 
LIMIT 5

+--------+
| amount |
|--------|
| 2.99   |
| 0.99   |
| 5.99   |
| 0.99   |
| 9.99   |
+--------+

从现有表确定数据类型

SELECT 
    title, 
    description, 
    special_features 
FROM FILM 
LIMIT 5

+---------------+------------------+------------------------------+
| title         |  description     | special_features             |
|---------------|------------------|------------------------------|
| ACADEMY D...  | A Epic...        | {Deleted Scenes,Behi...}     |
| ACE GOLD...   | A Astound..      | {Trailers,Deleted Scenes}    |
| AFFAIR PR...  | A Fanciful,..    | {Commentaries,Behind the...} |
+---------------+------------------+------------------------------+

从现有表确定数据类型

SELECT
    column_name, 
    data_type
FROM INFORMATION_SCHEMA.COLUMNS 
WHERE column_name in ('title','description','special_features')
  AND table_name ='film';

+------------------+-------------------+
| column_name      | data_type         |
|------------------+-------------------|
| title            | character varying |
| description      | text              |
| special_features | ARRAY             |
+------------------+-------------------+

Vamos praticar!

在 PostgreSQL 中使用函数处理数据