Question

使用连接从两个表中选择数据时，如何从一行中获取mysql查询中的数据？

"id"    "itemId"    "itemTempId"    "itemName"                  "userId" "postId"
"1"     "US1"       "T001"          "Samsung Galaxy Note 5"     "1"      "1"

"id"    "itemId"    "itemTempId"    "itemImageName"     "userId" "postId"
"1"     "US1"       "T001"          "front.jpg"         "1"      "1"
"2"     "US1"       "T001"          "side-left.jpg"     "1"      "1"
"3"     "US1"       "T001"          "side-right.jpg"    "1"      "1"
"4"     "US1"       "T001"          "back.jpg"          "1"      "1"

现在，当我在下面选择第一个表中的1行和第二个表中的相关行时，我会得到每一行中的所有数据，当我使用php打印时，它也会重复。

select a.itemName, b.itemImageName from amga a left join amgb b on a.userId = b.userId where a.userId = 1;

当前输出

"itemName"                  "itemImageName"
"Samsung Galaxy Note 5"     "front.jpg"
"Samsung Galaxy Note 5"     "side-left.jpg"
"Samsung Galaxy Note 5"     "side-right.jpg"
"Samsung Galaxy Note 5"     "back.jpg"

理想输出或其他一些不会重复itemName且可以使用php轻松输出的变体。

"itemName"                  "itemImageName"
"Samsung Galaxy Note 5"     "front.jpg","side-left.jpg","side-right.jpg","back.jpg"

在最终结果中，标题仅输出一次，而图像名称需要循环播放。像这样：

"Samsung Galaxy Note 5"
"front.jpg","side-left.jpg","side-right.jpg","back.jpg"

Answer 1

select a.itemName, GROUP_CONCAT(b.itemImageName) 
from amga a 
left join amgb b 
on a.userId = b.userId 
where a.userId = 1
group by a.itemName

如果您不想复制，请在GROUP_CONCAT中使用DISTINCT。

Answer 2

您需要使用GROUP_CONCAT功能进行分组。请尝试此查询：

select a.itemName, group_concat(b.itemImageName) 
from amga a left join amgb b on a.userId = b.userId 
where a.userId = 1 
group by a.itemName;

Answer 3

group_concat运算符是您正在寻找的内容：

SELECT    item_name, GROUP_CONCAT(item_image_name)
FROM      amga
LEFT JOIN amgb ON amga.userId = b.userId
WHERE     amge.userId = 1
GROUP BY  item_name

在mysql中使用select join时选择数据作为单行

3 个答案: