我被困在一個查詢在mysql中

Question

我被困在一個查詢在mysql中。

我想從表

• 獲取最近期的評論的評論應該是最近的評論的博客
• 博客應該是最新的3個博客。只有當他們的狀態是啓用

記錄應該像表的表博客這個
表結構

顯示評論&博客

---

 
blog_id int - primary (auto increment) 
blog_title  -varchar 
blog_desc  -varchar 
blog_image  -varchar 
blog_tags  -varchar 
tot_comments  -int 
blog_creater  -varchar 
blog_create_date -datetime 
blog_status  -enum ('Enable','Disable') 

爲表表結構blog_comment

---

 
comment_id  -int (auto increment) 
fk_blog_id  -int 
comment   -varchar 
comment_by  -varchar 
email   -varchar 
comment_date  -datetime 
comment_status -enum ('Enable','Disable') 

及以下查詢我寫的，但我得到的結果是錯誤的。

SELECT b.blog_title,b.blog_image, bc.* 
FROM blog_comments bc, blog b 
WHERE bc.comment_status='Enable' 
AND b.blog_status='Enable' 
AND b.blog_id=bc.fk_blog_id 
GROUP BY bc.fk_blog_id  
ORDER BY bc.comment_date DESC 
LIMIT 0,3 

輸出

---

Answer 1

爲此，簡單的解決方案將執行2查詢您的結果。第一個查詢獲得博客帖子結果

$db_blog="select blog_id,blog_title from blog where blog_ststus='Enable'"; 
$que=mysql_query($db_blog); 
while($row=mysql_fetch_object($que)) 
{ 
    echo $row->blog_title; 
    $db_comment="select comment from blog_comments where fk_blog_id=".$row->blog_id." and comment_status='Enable' order by comment_date desc"; 
    $quec=mysql_query($db_comment); 
    while($comment=mysql_fetch_object($quec)) 
    { 
     echo $comment->comment; 
    } 
} 

Answer 2

嘗試

SELECT b.blog_title,b.blog_image, bc.* 
FROM blog_comments AS bc, blog AS b 
WHERE bc.comment_status='Enable' 
AND b.blog_status='Enable' 
AND b.blog_id=bc.fk_blog_id 
GROUP BY bc.fk_blog_id  
ORDER BY bc.comment_date DESC 
LIMIT 0,3; 

（我不是100％確定）

Answer 3

SELECT b.blog_title,b.blog_image, bc.* 
FROM blog b 
left join (
Select * from 
blog_comments bc 
WHERE bc.comment_status='Enable' 
GROUP BY bc.fk_blog_id  
having max(bc.comment_date) = bc.comment_date 
) bcc on b.blog_id=bcc.fk_blog_id 
where 
b.blog_status='Enable' 
ORDER BY b.blog_create_date desc 
LIMIT 0,3 

試試這個

Answer 4

SELECT b.blog_title,b.blog_image, bc.* 
FROM blog_comments bc JOIN blog b ON bc.fk_blog_id = b.blog_id 
WHERE bc.comment_status='Enable' 
AND b.blog_status='Enable' 
GROUP BY bc.fk_blog_id  
ORDER BY bc.comment_date DESC 
LIMIT 0,3 

Answer 5

試試這個：

SELECT * FROM blog_comments bc, blog b 
WHERE `bc.comment_status`='Enable' 
AND `b.blog_status`='Enable' 
AND `b.blog_id`=bc.fk_blog_id 
ORDER BY `bc.comment_date` DESC LIMIT 1; 

嘗試一個更簡單的一個：

SELECT * FROM `blog_comment` WHERE 'blog_status'='Enable' AND 'blog_id'='$blogidherefromtitle' ORDER BY 'comment_date' DESC LIMIT1 

Answer 6

嘗試此查詢

SELECT 
    bc.* 
FROM 
    blog AS b 
    INNER JOIN (SELECT id , MAX(id) AS MaxID FROM blog) AS bl ON bl.id = b.id 
    LEFT JOIN blog_comment AS bc ON bc.fk_blog_id = b.id 
ORDER BY bc.comment_id DESC 
LIMIT 3  

個EDITS：

SELECT 
    bc.* 
FROM 
    blog AS b 
    INNER JOIN (SELECT id , MAX(id) AS MaxID FROM blog GROUP BY id) AS bl ON bl.id = b.id 
    INNER JOIN (SELECT MAX(id) , fk_blog_id FROM blog_comment GROUP BY id) AS bc ON bc.fk_blog_id = b.id 
ORDER BY bc.comment_id DESC 
LIMIT 3 

這是使用內部連接將獲取最新的博客每個博客

這裏3個最新的博客和最新單曲評論。比加入評論和命令他們與日期或ID和限制他們根據您的要求。

Answer 7

select b.blog_title, b.blog_image, bc.* 
from blog b join 
(select bc.* 
from bc join (select fk_blog_id, max(comment_date) latest_date 
       from blog_comment 
       where comment_status = 'Enable' 
       group by fk_blog_id) latest 
on bc.fk_blog_id = latest.fk_blog_id and bc.comment_date = latest_date) c 
on b.blog_id = c.fk_blog_id 
where b.blog_status = 'Enable' 
order by c.comment_date desc 
limit 0, 3 

的c子查詢中找到與每個博客的最新評論的行，使用鏈接的問題的技術。然後加入blog表以獲取適當的博客數據。