[英]How to get unique data from two tables using mysql?
我有兩個表,一個表有項目的詳細信息是唯一的,另一個表有這個項目的圖像,但有多個。
我想要一個項目的一個圖像。
數據結構:
Table 1:
Project_id Project_Name
291 Demo1
292 Demo2
Table 2:
Project_id Img_name Attr_id
291 p1.png 11
291 p2.png 12
我想得到attr_id為11的圖像
所以輸出會是
project_id Project_name Img_name Attr_id
291 Demo1 p1.png 11
那怎么做?
在你的情況下你可以使用mysql的JOIN
函數:
SELECT a.Project_id, a.Project_Name, b.Img_name, b.Attr_id
FROM table2 b INNER JOIN Table1 a ON ( b.Project_id = a.Project_id)
WHERE b.Attr_id = 11
或者您可以通過WHERE ... AND
-Construction過濾您的選擇:
select * from table1 a,table2 b where a.project_id = b.project_id and attr_id=11
兩種方式都會產生相同的輸出:
291 Demo1 p1.png 11
你可以有一個join
這兩個表用於獲取結果:
"select t1.project_id,t1.project_name,t2.img_name,t2.attr_id
from table1 t1,table2 t2
where t1.project_id=t2.project_id
and t2.attr_id=11";
如果您不想專門查詢Attr_id,請嘗試使用此方法。 應該為您提供與項目相關的最低Attr_id的圖像
SELECT table1.project_id, table1.project_name, image.Img_name, image.Attr_id
FROM table1
INNER JOIN (SELECT * FROM table2 ORDER BY Attr_id ASC LIMIT 1)
AS image ON table1.project_id = image.project_id
WHERE table1.project_id = 291
使用mysql JOIN
select a.Project_id,a.Project_Name,b.Img_name,b.Attr_id from table1 a join table2 b ON a.project_id = b.project_id where b.attr_id=11
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.