3.1 排序数据
子句（clause）
SQL语句由子句构成。一个子句通常由一个关键字加上所提供的数据组成。 ORDER BY子句可以取一个或多个列的名字，将SELECT语句检索出的数据进行排序。 ORDER BY子句可以使用非检索的列排序数据。 ORDER BY子句必须作为SELECT语句中最后一条子句。MariaDB [sqlbzbh]> SELECT prod_name FROM Products ORDER BY prod_name;+---------------------+| prod_name |+---------------------+| 12 inch teddy bear || 18 inch teddy bear || 8 inch teddy bear || Bird bean bag toy || Fish bean bag toy || King doll || Queen doll || Rabbit bean bag toy || Raggedy Ann |+---------------------+9 rows in set (0.00 sec)MariaDB [sqlbzbh]> MariaDB [sqlbzbh]> SELECT prod_name FROM Products ORDER BY vend_id;+---------------------+| prod_name |+---------------------+| 8 inch teddy bear || 12 inch teddy bear || 18 inch teddy bear || Fish bean bag toy || Bird bean bag toy || Rabbit bean bag toy || Raggedy Ann || King doll || Queen doll |+---------------------+9 rows in set (0.00 sec)MariaDB [sqlbzbh]>
3.2 按多个列排序
要按多个列排序，简单指定列名，列名之间用逗号分开即可。
在按多个列排序时，排序的顺序完全按规定进行。也就是说，仅在前一列的多个行具有相同的值时，才按照下一列进行排序。MariaDB [sqlbzbh]> SELECT prod_id,prod_price,prod_name FROM Products ORDER BY prod_price,prod_name;+---------+------------+---------------------+| prod_id | prod_price | prod_name |+---------+------------+---------------------+| BNBG02 | 3.49 | Bird bean bag toy || BNBG01 | 3.49 | Fish bean bag toy || BNBG03 | 3.49 | Rabbit bean bag toy || RGAN01 | 4.99 | Raggedy Ann || BR01 | 5.99 | 8 inch teddy bear || BR02 | 8.99 | 12 inch teddy bear || RYL01 | 9.49 | King doll || RYL02 | 9.49 | Queen doll || BR03 | 11.99 | 18 inch teddy bear |+---------+------------+---------------------+9 rows in set (0.00 sec)MariaDB [sqlbzbh]>
3.3 按列位置排序
ORDER BY支持按相对列位置进行排序。
优点是不用重新输入列名，缺点是容易造成错误排序。个人不建议使用。 如果有必要，可以混合使用实际列名和相对列位置。MariaDB [sqlbzbh]> SELECT prod_id,prod_price,prod_name FROM Products ORDER BY 2,3;+---------+------------+---------------------+| prod_id | prod_price | prod_name |+---------+------------+---------------------+| BNBG02 | 3.49 | Bird bean bag toy || BNBG01 | 3.49 | Fish bean bag toy || BNBG03 | 3.49 | Rabbit bean bag toy || RGAN01 | 4.99 | Raggedy Ann || BR01 | 5.99 | 8 inch teddy bear || BR02 | 8.99 | 12 inch teddy bear || RYL01 | 9.49 | King doll || RYL02 | 9.49 | Queen doll || BR03 | 11.99 | 18 inch teddy bear |+---------+------------+---------------------+9 rows in set (0.00 sec)MariaDB [sqlbzbh]>
3.4 制定排序方向
默认的排序顺序是升序排序（从A到Z）。
可以使用ORDER BY子句进行降序排序（从Z到A），但必须指定DESC关键字。 DESC关键字只应用到直接位于其前面的列名。如果想在多个列上进行降序排序，必须对每一列指定DESC关键字。 DESC是DESCENDING的缩写，这两个关键字都可以使用。 ASC是ASCENDING的缩写，因为升序是默认的，所以不必指定关键字。MariaDB [sqlbzbh]> SELECT prod_id,prod_price,prod_name FROM Products ORDER BY prod_price;+---------+------------+---------------------+| prod_id | prod_price | prod_name |+---------+------------+---------------------+| BNBG01 | 3.49 | Fish bean bag toy || BNBG02 | 3.49 | Bird bean bag toy || BNBG03 | 3.49 | Rabbit bean bag toy || RGAN01 | 4.99 | Raggedy Ann || BR01 | 5.99 | 8 inch teddy bear || BR02 | 8.99 | 12 inch teddy bear || RYL01 | 9.49 | King doll || RYL02 | 9.49 | Queen doll || BR03 | 11.99 | 18 inch teddy bear |+---------+------------+---------------------+9 rows in set (0.00 sec)MariaDB [sqlbzbh]> MariaDB [sqlbzbh]> SELECT prod_id,prod_price,prod_name FROM Products ORDER BY prod_price DESC;+---------+------------+---------------------+| prod_id | prod_price | prod_name |+---------+------------+---------------------+| BR03 | 11.99 | 18 inch teddy bear || RYL01 | 9.49 | King doll || RYL02 | 9.49 | Queen doll || BR02 | 8.99 | 12 inch teddy bear || BR01 | 5.99 | 8 inch teddy bear || RGAN01 | 4.99 | Raggedy Ann || BNBG01 | 3.49 | Fish bean bag toy || BNBG02 | 3.49 | Bird bean bag toy || BNBG03 | 3.49 | Rabbit bean bag toy |+---------+------------+---------------------+9 rows in set (0.00 sec)MariaDB [sqlbzbh]> MariaDB [sqlbzbh]> SELECT prod_id,prod_price,prod_name FROM Products ORDER BY prod_price DESC, prod_name;+---------+------------+---------------------+| prod_id | prod_price | prod_name |+---------+------------+---------------------+| BR03 | 11.99 | 18 inch teddy bear || RYL01 | 9.49 | King doll || RYL02 | 9.49 | Queen doll || BR02 | 8.99 | 12 inch teddy bear || BR01 | 5.99 | 8 inch teddy bear || RGAN01 | 4.99 | Raggedy Ann || BNBG02 | 3.49 | Bird bean bag toy || BNBG01 | 3.49 | Fish bean bag toy || BNBG03 | 3.49 | Rabbit bean bag toy |+---------+------------+---------------------+9 rows in set (0.00 sec)MariaDB [sqlbzbh]>