SQL查询来挑选每个ID

Question

我需要选择每个产品的第一拇指图像（在这里它的实体ID）

我的查询

SELECT entity_id as product_id, value FROM catalog_product_entity_media_gallery 

的一个形象，但它回来时，我需要查询到的所有图像从每个ID挑选第一张图片可以提供任何帮助。

db table

Answer 1

SELECT entity_id as product_id, value FROM catalog_product_entity_media_gallery GROUP BY entity_id 

Answer 2

可以限制返回行从有限度的0指数开始1分的纪录。

SELECT entity_id as product_id,value FROM catalog_product_entity_media_gallery GROUP BY entity_id 

Answer 3

试试这个，使用GROUP BY为获得第一个

SELECT entity_id as product_id, value FROM catalog_product_entity_media_gallery GROUP BY entity_id ORDER BY entity_id 

Answer 4

你面包车使用GROUP BY条款

SELECT entity_id as product_id, value FROM catalog_product_entity_media_gallery 
GROUP BY entity_id ORDER BY entity_id 

ORDER BY ENTITY_ID取分组和顺序它们第一个拇指图像

Answer 5

下面是该查询

SELECT entity_id as product_id, value FROM catalog_product_entity_media_gallery GROUP BY product_id ORDER BY `value_id` ASC 

当你在做GROUP BY你把所有的类似 的product_id或ENTITY_ID一个&为你ORDER BY value_id由 登高首先插入的行将在顶部，并按

检查这两个链接了解更多详情http://www.w3schools.com/sql/sql_groupby.asp & http://www.w3schools.com/sql/sql_orderby.asp