如何使用内部连接php(计数)获取属于post的总行数?
我使用内部连接列出帖子及其类别和评论, 像这样:如何使用内部连接php(计数)获取属于post的总行数?,php,mysqli,Php,Mysqli,我使用内部连接列出帖子及其类别和评论, 像这样: if($stmt = $pdo->prepare("SELECT * FROM posts INNER JOIN categories ON posts.cat_id = categories.cat_id INNER JOIN comments ON posts.post_id = comment_id WHERE user_id = :sid")){ $stmt->execute(arr
if($stmt = $pdo->prepare("SELECT * FROM posts
INNER JOIN categories ON posts.cat_id = categories.cat_id
INNER JOIN comments ON posts.post_id = comment_id
WHERE user_id = :sid")){
$stmt->execute(array('sid'=>$sid));
然后执行while循环以列出它们
while($row = $stmt->fetch(PDO::FETCH_ASSOC)){
usaqe是:
$row['category'];
我想获得属于帖子的评论总行数,并将其显示为:
帖子评论总数:$row['Total_coments'
有可能吗?您可以这样做,假设注释id是唯一的
if($stmt = $pdo->prepare("SELECT posts.*,(select count(comment_id) from
comments)
as total_coments
FROM posts
INNER JOIN categories ON posts.cat_id = categories.cat_id
INNER JOIN comments ON posts.post_id = comment_id
WHERE user_id = :sid")){
$stmt->execute(array('sid'=>$sid));
当我像这样使用它时:SELECT posts.*,SELECT countcomment\u id from comments as total\u coments然后它忽略类别,有错误未定义索引:cat\u name有相同的错误,我尝试了这种方式“posts.*,categories.*,comments.*”`现在可以工作了,非常感谢budd。