SQL ORDER BY 关键字

ORDER BY 关键字用于对结果集进行排序。

## 语法

ORDER BY 关键字用于对结果集按照一个列或者多个列进行排序。

ORDER BY 关键字默认按照升序对记录进行排序。如果需要按照降序对记录进行排序，您可以使用 DESC 关键字。

```sql
SELECT column_name,column_name
FROM table_name
ORDER BY column_name,column_name ASC|DESC;
```

### 演示数据库

在本教程中，我们将使用众所周知的 Northwind 样本数据库。

下面是选自 "Customers" 表的数据：

| CustomerID | CustomerName | ContactName | Address | City | PostalCode | Country |
| --- | --- | --- | --- | --- | --- | --- |
| 1 | Alfreds Futterkiste | Maria Anders | Obere Str. 57 | Berlin | 12209 | Germany |
| 2 | Ana Trujillo Emparedados y helados | Ana Trujillo | Avda. de la Constitución 2222 | México D.F. | 05021 | Mexico |
| 3 | Antonio Moreno Taquería | Antonio Moreno | Mataderos 2312 | México D.F. | 05023 | Mexico |
| 4 | Around the Horn | Thomas Hardy | 120 Hanover Sq. | London | WA1 1DP | UK |
| 5 | Berglunds snabbköp | Christina Berglund | Berguvsvägen 8 | Luleå | S-958 22 | Sweden |

## 实例

### ORDER BY 实例

下面的 SQL 语句从 "Customers" 表中选取所有客户，并按照 "Country" 列排序：

```sql
SELECT * FROM Customers
ORDER BY Country;
```

### ORDER BY DESC 实例

下面的 SQL 语句从 "Customers" 表中选取所有客户，并按照 "Country" 列降序排序：

```sql
SELECT * FROM Customers
ORDER BY Country DESC;
```

### ORDER BY Several Columns 实例

下面的 SQL 语句从 "Customers" 表中选取所有客户，并按照 "Country" 和 "CustomerName" 列排序：

```sql
SELECT * FROM Customers
ORDER BY Country,CustomerName;
```