如何使用一個MySQL查詢選擇帶有標籤和全部文章標籤的所有文章？

我有3個表格：文章（id，標題，內容），標籤（id，tag）和tags2all（id，iditem，idtag，模塊）。我想選擇具有特定標籤的所有文章，但在結果列表中，我希望能夠顯示每篇文章的標籤。如何使用一個MySQL查詢選擇帶有標籤和全部文章標籤的所有文章？

目前我使用這個查詢，顯示的文章列表：

SELECT GROUP_CONCAT(t.tag SEPARATOR ', ') AS tags,a.* FROM articles AS a LEFT JOIN tags2all AS ta ON ta.iditem=a.id AND ta.module='articles' JOIN tags AS t ON ta.idtag=t.id GROUP BY a.id HAVING a.title IS NOT NULL

看來工作相當不錯，但我似乎無法弄清楚如何添加到查詢顯示只有具有特定標籤的文章。

如果我添加WHERE t.id = 3，它會選擇正確的文章，但標籤列表將只包含該標籤。

來源

2011-12-23 pandronic

這似乎爲我工作確定：

select a.* 
from 
(
SELECT GROUP_CONCAT(t.tag SEPARATOR ', ') AS tags,a.id,a.title,a.content 
FROM articles AS a LEFT JOIN tags2all AS ta ON ta.iditem=a.id 
AND ta.module='articles' JOIN tags AS t ON ta.idtag=t.id 
GROUP BY a.id HAVING a.title IS NOT NULL 
) a inner join tags2all t2a on t2a.iditem = a.id 
inner join tags t on t.id = t2a.idtag 
where t.id = 3;

這裏的DDL和數據我用：

create table articles (id int unsigned not null primary key, title varchar(50), content varchar(50)); 

create table tags (id int unsigned not null primary key, tag varchar(50)); 

create table tags2all (id int unsigned not null primary key, iditem int unsigned not null, idtag int unsigned not null, module varchar(50)); 

insert into articles values (1,"Article1","Some content"); 
insert into articles values (2,"Article2","Some content"); 
insert into articles values (3,"Article3","Some content"); 

insert into tags values (1,"Tag1"); 
insert into tags values (2,"Tag2"); 
insert into tags values (3,"Tag3"); 
insert into tags values (4,"Tag4"); 
insert into tags values (5,"Tag5"); 
insert into tags values (6,"Tag6"); 
insert into tags values (7,"Tag7"); 

insert into tags2all (id,iditem,idtag,module) values (1,1,1,"articles"); 
insert into tags2all (id,iditem,idtag,module) values (2,1,2,"articles"); 
insert into tags2all (id,iditem,idtag,module) values (3,1,3,"articles"); 
insert into tags2all (id,iditem,idtag,module) values (4,2,3,"articles"); 
insert into tags2all (id,iditem,idtag,module) values (5,2,4,"articles"); 
insert into tags2all (id,iditem,idtag,module) values (6,2,5,"articles"); 
insert into tags2all (id,iditem,idtag,module) values (7,3,3,"articles"); 
insert into tags2all (id,iditem,idtag,module) values (8,3,4,"articles"); 
insert into tags2all (id,iditem,idtag,module) values (9,3,7,"articles");

來源

2011-12-23 07:58:25

我不知道，但讓我們嘗試

SELECT GROUP_CONCAT(t.tag SEPARATOR ', ') AS tags,a.* FROM articles AS a 
LEFT JOIN tags2all AS ta ON ta.iditem=a.id AND ta.module='articles' 
JOIN tags AS t ON ta.idtag=t.id 
JOIN tags AS t1 ON ta1.idtag=t.id 
GROUP BY a.id HAVING a.title IS NOT NULL

來源

2011-12-23 07:48:52 hungneox

如何使用一個MySQL查詢選擇帶有標籤和全部文章標籤的所有文章？

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