PostgreSQL ORDER BY
在 PostgreSQL 中,ORDER BY 用于对一列或者多列数据进行升序(ASC)或者降序(DESC)排列。
语法
ORDER BY 子句的基础语法如下:
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,但是必须保证要排序的列必须存在。
ASC 表示升序,DESC 表示降序。
实例
创建 COMPANY 表(下载 COMPANY SQL 文件 ),数据内容如下:
jsondb# 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)
下面实例将对结果根据 AGE 字段值进行升序排列:
jsondb=# SELECT * FROM COMPANY ORDER BY AGE ASC;
得到以下结果:
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)
下面实例将对结果根据 NAME 字段值和 SALARY 字段值进行升序排序:
jsondb=# SELECT * FROM COMPANY ORDER BY NAME, SALARY ASC;
得到以下结果:
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)
下面实例将对结果根据NAME字段值进行降序排列:
jsondb=# SELECT * FROM COMPANY ORDER BY NAME DESC;
得到以下结果:
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)