具有一个DISTINCT字段的MySQL SELECT语句 [英] MySQL SELECT statment with one DISTINCT field

问题描述

我有一个汽车列表，每辆汽车都有一个 make 和 model 列.我想从列表中提取一个独特的品牌/型号组合列表.

I have a list of cars with each car having a make and model column. I would like to extract a list of unique make/model combinations from the list.

例如，可能有3辆Audi A3汽车，一辆红色，一辆蓝色等.我希望查询返回"Audi A3"是有效的品牌/型号，无论它出现多少次.

For example, there might be 3 x Audi A3 vehicles, one red, one blue etc. I would like the query to return that 'Audi A3' is a valid make/model regardless of how many times it appears.

这是我尝试的查询:

SELECT make, DISTINCT model FROM bs_cars ORDER BY make, model ASC

我试图将 DISTINCT 应用于 model ，因为 make 可能具有多种模型.

I have tried to apply DISTINCT to model only as make would potentially have various models under it.

推荐答案

DISTINCT 选项适用于行级别，仅从一列中选择不同的值是没有意义的.这就是为什么它会保留在 SELECT 子句中出现的任何表达式之前的原因.

The DISTINCT option applies at the row level, there is no point selecting distinct values only from one column. This is why it stays before any expression that appears in the SELECT clause.

它将从输出中删除重复的行，并保留表中任何对( make ， model )的单个实例.

It removes the duplicate rows from the output, keeping a single instance of any pair (make, model) you have in the table.

SELECT DISTINCT make, model
FROM bs_cars
ORDER BY make, model ASC

检查文档: http://dev.mysql.com/doc/refman/5.7/en/select.html

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