php - 如何内连接三个表并获取计数

Question

我有三个表:

members (id, name, surname, usr_img)

user_uploads (imgID, user_id, filename, description, up_time)

img_likes (likeID, img_id, user_id)

我需要从 user_uploads 获取所有信息，并使用 img_id，从成员处获取上传者信息，并在 img_likes 表中进行 2 次计数(检查 user_id(来自 session 变量)和 img_id 是否存在，并获取 img 总喜欢数)。

SELECT user_uploads.* AS uu, members.*, COUNT(img_id, user_id) AS usr_liked, COUNT(img_id) AS total_likes
FROM user_uploads
INNER JOIN members AS m ON m.id = uu.user_id -- owner info
INNER JOIN img_likes AS il ON il.img_id = uu.imgID AND il.user_id = ? -- check if logged in user already liked
INNER JOIN img_likes AS ilt ON ilt.img_id = uu.imgID -- total likes
GROUP BY img_id, user_id
ORDER BY up_time DESC

我不需要从 img_id 获取任何内容，只需计算行数即可。我不知道是否需要内部联接，也许是为了指定 user_id？

并获取计数:

$usr_liked = row['usr_liked'];
$total_likes = rwo['total_likes'];

这行得通吗？

编辑:添加新查询:

SELECT
    user_uploads.*,
    (
        SELECT *
        FROM members m
        WHERE m.id = user_uploads.user_id
    ),
    (
        SELECT COUNT(*)
        FROM img_likes t
        WHERE t.img_id = user_uploads.imgID AND t.user_id = ?
    ) AS user_likes,
    (
        SELECT COUNT(*)
        FROM img_likes t
        WHERE t.img_id = user_uploads.imgID
    ) AS total_likes
FROM user_uploads
ORDER BY up_time DESC

Answer 1

您可以使用子查询:

SELECT 
    uu.*, 
    m.*,
    (
        SELECT COUNT(t.*)
        FROM img_likes t
        WHERE t.img_id = uu.imgID AND t.user_id = ?
    ) AS user_likes,
    (
        SELECT COUNT(t.*)
        FROM img_likes t
        WHERE t.img_id = uu.imgID 
    ) AS total_likes
FROM 
    user_uploads AS uu
    INNER JOIN members AS m ON 
        m.id = uu.user_id
ORDER BY
    uu.up_time DESC