PostgreSQL ORDER BY 语句
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:
yssmxdb# 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:
yssmxdb=# 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:
yssmxdb=# 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:
yssmxdb=# 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)