mysql - 选择不同操作数应包含 1 列

Question

mysql> 从产品中选择*；

    +----+-------------+-------+---------------------+----------+
    | id | prod        | code  | name                | prodstat | 
    +----+-------------+-------+---------------------+----------+
    |  1 | ACCESSORIES | 2810  | Dish Rack           | 1        |
    |  2 | ACCESSORIES | 2816  | Saucer Rack         | 1        |
    |  3 | ACCESSORIES | 2830  | Drying Crate        | 1        |
    |  4 | ACCESSORIES | 2820  | Big Crate Cover     | 1        |
    |  5 | ACCESSORIES | 2826  | Scallop Crate Cover | 1        |
    |  6 | ACCESSORIES | 2828  | Mini Crate Cover    | 1        | 
    |  7 | ACCESSORIES | 2839  | Small Goblet Cover  | 1        |
    |  8 | ACCESSORIES | 2878  | Harvest Crate Cover | 1        |
    |  9 | CRATES      | 1688N | Big Crate New       | 1        |
    +----+-------------+-------+---------------------+----------+
    9 rows in set (0.00 sec)
     select distinct(prod, code, name) as Prod from product;
ERROR 1241 (21000): Operand should contain 1 column(s)

需要如下结果:

|Prod|
|ACCESSORIES 2810 Dish Rack|

Answer 1

删除括号:

select distinct prod, code, name
from product;

distinct 不是一个函数。 select unique 是一个子句，distinct 适用于所有参数。

如果要将三列合并为一列，请使用 concat() 或 concat_ws():

select distinct concat_ws(' ', prod, code, name) as Prod
from product;

(distinct 可能不是必需的。)