SELECT查询结果排序

1.排序数据

使用SELECT 的order by子句能够对查询结果进行排序。

确保ORDER BY子句在SELECT语句的最后，不然会出现错误。

示例：

查询产品名称并以字母顺序排序：

mysql> 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 | +---------------------+
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以价格升序排序：

mysql> SELECT prod_name,prod_price from Products ORDER BY prod_price; +---------------------+------------+
| prod_name | prod_price | +---------------------+------------+
| Fish bean bag toy   |       3.49 |
| Bird bean bag toy   |       3.49 |
| Rabbit bean bag toy |       3.49 |
| Raggedy Ann         |       4.99 |
| 8 inch teddy bear   |       5.99 |
| 12 inch teddy bear  |       8.99 |
| King doll           |       9.49 |
| Queen doll          |       9.49 |
| 18 inch teddy bear | 11.99 | +---------------------+------------+
9 rows in set (0.00 sec)

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价格降序排序：

mysql> SELECT prod_name,prod_price FROM Products ORDER BY prod_price DESC; +---------------------+------------+
| prod_name | prod_price | +---------------------+------------+
| 18 inch teddy bear  |      11.99 |
| King doll           |       9.49 |
| Queen doll          |       9.49 |
| 12 inch teddy bear  |       8.99 |
| 8 inch teddy bear   |       5.99 |
| Raggedy Ann         |       4.99 |
| Fish bean bag toy   |       3.49 |
| Bird bean bag toy   |       3.49 |
| Rabbit bean bag toy | 3.49 | +---------------------+------------+
9 rows in set (0.00 sec)

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2.按多个列排序

按多个列排序的时候，先按第一列排序，第一列中有相同值，相同值的记录再按第二列排序；若是第一列都是惟一的，则再也不按第二列排序。以下示例：

mysql> 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)

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上面查询先依据价格排序，价格相同的按prod_name字典顺序排序。 
也能够使用位置代替排序列名，上述sql语句还能够这样写：

mysql> SELECT prod_id,prod_price,prod_name FROM  Products ORDER BY 2,3;

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使用位置表明列名，优势是不用从新输入列名，缺点是列名更改时会形成错误。

升序和降序

ORDER BY查询默认是升序排序，降序能够加上DESC,好比按价格由高到低排序：

mysql> 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)

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DESC只对在它前面的一个列名有做用，MySQL> SELECT prod_id,prod_price,prod_name FROM Products ORDER BY prod_price,prod_name DESC;对prod_price无效：

mysql> SELECT prod_id,prod_price,prod_name FROM Products ORDER BY prod_price,prod_name DESC; +---------+------------+---------------------+
| prod_id | prod_price | prod_name | +---------+------------+---------------------+
| BNBG03  |       3.49 | Rabbit bean bag toy |
| BNBG01  |       3.49 | Fish bean bag toy   |
| BNBG02  |       3.49 | Bird bean bag toy   |
| RGAN01  |       4.99 | Raggedy Ann         |
| BR01    |       5.99 | 8 inch teddy bear   |
| BR02    |       8.99 | 12 inch teddy bear  |
| RYL02   |       9.49 | Queen doll          |
| RYL01   |       9.49 | King doll           |
| BR03 | 11.99 | 18 inch teddy bear | +---------+------------+---------------------+
9 rows in set (0.00 sec)