SQL查詢來挑選每個ID

Question

我需要選擇每個產品的第一拇指圖像（在這裏它的實體ID）

我的查詢

SELECT entity_id as product_id, value FROM catalog_product_entity_media_gallery 

的一個形象，但它回來時，我需要查詢到的所有圖像從每個ID挑選第一張圖片可以提供任何幫助。

db table

Answer 1

SELECT entity_id as product_id, value FROM catalog_product_entity_media_gallery GROUP BY entity_id 

Answer 2

可以限制返回行從有限度的0指數開始1分的紀錄。

SELECT entity_id as product_id,value FROM catalog_product_entity_media_gallery GROUP BY entity_id 

Answer 3

試試這個，使用GROUP BY爲獲得第一個

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

Answer 4

你麪包車使用GROUP BY條款

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取分組和順序它們第一個拇指圖像

Answer 5

下面是該查詢

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

當你在做GROUP BY你把所有的類似 的product_id或ENTITY_ID一個&爲你ORDER BY value_id由 登高首先插入的行將在頂部，並按

檢查這兩個鏈接瞭解更多詳情http://www.w3schools.com/sql/sql_groupby.asp & http://www.w3schools.com/sql/sql_orderby.asp