distinct.md

# Distinct

Joe 想统计以下 goods 表

```sql
create table goods(
    id int primary key auto_increment,
    category_id int,
    category varchar(64),
    name varchar(256),
    price decimal(12, 4),
    stock int,
    upper_time timestamp
)
```

中的商品有多少种不同的价格，他应该如何写这条查询？

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## 答案

```sql
select count(distinct price) from goods;
```

## 选项

### A

```sql
select count(distinct *) from goods;
```

### B

```sql
select distinct count(price) from goods;
```

### C

```sql
select count(price) from goods;
```

### D

```sql
select distinct price from goods;
```