在 PostgreSQL 中，ORDER BY 用于對一列或者多列數(shù)據(jù)進行升序(ASC)或者降序(DESC)排列。
ORDER BY 子句的基礎語法如下：
SELECT column-list FROM table_name [WHERE condition] [ORDER BY column1, column2, .. columnN] [ASC | DESC];
您可以在 ORDER BY 中使用一列或者多列，但是必須保證要排序的列必須存在。
ASC 表示升序，DESC 表示降序。
創(chuàng)建 COMPANY 表（下載 COMPANY SQL 文件 ），數(shù)據(jù)內容如下：
nhooodb# select * from COMPANY; id | name | age | address | salary ----+-------+-----+-----------+-------- 1 | Paul | 32 | California| 20000 2 | Allen | 25 | Texas | 15000 3 | Teddy | 23 | Norway | 20000 4 | Mark | 25 | Rich-Mond | 65000 5 | David | 27 | Texas | 85000 6 | Kim | 22 | South-Hall| 45000 7 | James | 24 | Houston | 10000 (7 rows)
下面示例將對結果根據(jù) AGE 字段值進行升序排列：
nhooodb=# SELECT * FROM COMPANY ORDER BY AGE ASC;
得到以下結果：
id | name | age | address | salary ----+-------+-----+----------------------------------------------------+-------- 6 | Kim | 22 | South-Hall | 45000 3 | Teddy | 23 | Norway | 20000 7 | James | 24 | Houston | 10000 4 | Mark | 25 | Rich-Mond | 65000 2 | Allen | 25 | Texas | 15000 5 | David | 27 | Texas | 85000 1 | Paul | 32 | California | 20000 (7 rows)
下面示例將對結果根據(jù) NAME 字段值和 SALARY 字段值進行升序排序：
nhooodb=# SELECT * FROM COMPANY ORDER BY NAME, SALARY ASC;
得到以下結果：
id | name | age | address | salary ----+-------+-----+----------------------------------------------------+-------- 2 | Allen | 25 | Texas | 15000 5 | David | 27 | Texas | 85000 7 | James | 24 | Houston | 10000 6 | Kim | 22 | South-Hall | 45000 4 | Mark | 25 | Rich-Mond | 65000 1 | Paul | 32 | California | 20000 3 | Teddy | 23 | Norway | 20000 (7 rows)
下面示例將對結果根據(jù)NAME字段值進行降序排列：
nhooodb=# SELECT * FROM COMPANY ORDER BY NAME DESC;
得到以下結果：
id | name | age | address | salary ----+-------+-----+----------------------------------------------------+-------- 3 | Teddy | 23 | Norway | 20000 1 | Paul | 32 | California | 20000 4 | Mark | 25 | Rich-Mond | 65000 6 | Kim | 22 | South-Hall | 45000 7 | James | 24 | Houston | 10000 5 | David | 27 | Texas | 85000 2 | Allen | 25 | Texas | 15000 (7 rows)