mysql查询选项如何理解

create table t_6(

id int primary key auto_increment,

    goods_name varchar(50) not null,

    goods_price decimal(10,2) default 0.00,

    goods_color varchar(20),

    goods_weight int unsigned comment '重量，单位克'

)charset utf8;

insert into t_6 values(null,'mate10',5499.00,'blue',320),

(null,'mate10',5499.00,'gray',320),

(null,'nokia3301',1299,'black',420);

# 考虑所有字段的去重（不含逻辑主键）

select distinct goods_name,goods_price,goods_color,goods_weight from t_6;

select goods_name,goods_price,goods_color,goods_weight from t_6; # 保留所有

# 不考虑颜色去重

select distinct goods_name,goods_price,goods_weight from t_6;

select all goods_name,goods_price,goods_weight from t_6;