SQL FIRST() 函数

FIRST() 函数返回指定的列中第一个记录的值。

## 语法

```sql
SELECT FIRST(column_name) FROM table_name;
```

> 注释：只有 MS Access 支持 FIRST() 函数。

## SQL Server、MySQL 和 Oracle 中的 SQL FIRST() 工作区

### SQL Server 语法

```sql
SELECT TOP 1 column_name FROM table_name
ORDER BY column_name ASC;
```

### 实例

```sql
SELECT TOP 1 CustomerName FROM Customers
ORDER BY CustomerID ASC;
```

### MySQL 语法

```sql
SELECT column_name FROM table_name
ORDER BY column_name ASC
LIMIT 1;
```

### 实例

```sql
SELECT CustomerName FROM Customers
ORDER BY CustomerID ASC
LIMIT 1;
```

### Oracle 语法

```sql
SELECT column_name FROM table_name
ORDER BY  column_name ASC
WHERE ROWNUM <=1;
```

### 实例

```sql
SELECT CustomerName FROM Customers
ORDER BY CustomerID ASC
WHERE
ROWNUM <=1;
```

## 实例

### 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 |

下面的 SQL 语句选取 "Customers" 表的 "CustomerName" 列中第一个记录的值：

```sql
SELECT FIRST(CustomerName) AS FirstCustomer FROM Customers;
```