# 排序查询

## 1.仅仅排序

​ `order by`语句一般放在语句的最后面，进行限制

* `ASC`默认升序查询
* `DESC`降序查询

```sql
SELECT 
  * 
FROM
  `pmw_goodstype` 

ORDER BY id ASC;
```

## 2.排序筛选

```sql
SELECT 
  * 
FROM
  `pmw_goodstype` 

 WHERE `parentid` >1

ORDER BY id DESC;
```

按照表达式进行排序

* 通过`salary`进行表达式的计算
* `order By`支持别名

```sql
SELECT 
  id ,salary*12 AS year_salary
FROM
  `pmw_goodstype` 

 WHERE `parentid` >1

ORDER BY year_salary2 DESC;
```

## 3.多个排序条件

* 先出现的排序字段，优先级更高一些；这里当id字段相同时，按照`year_salary`进行降序排序

```sql
SELECT 
  id ,salary*12 AS year_salary
FROM
  `pmw_goodstype` 

 WHERE `parentid` >1

ORDER BY year_salary DESC, id ASC;
```


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