一起执行所有 SELECT 语句

Question

表格：

*shots*
id user_id cat_id name extension size title description library created updated

此表包含所有图片

---

favorites
id shot_id user_id date

此表包含所有添加的用户最喜欢的图像

---

stars
id shot_id user_id date

此表包含所有给定的用户图像的星星

---

views
id shot_id user_id date

此表包括每个用户的每个视图

---

points
id shot_id count date

用户的每一个动作（addFavvorite、giveStar、viewShot）都会为特定镜头加分

---

是否可以一次完成以下查询？

SELECT * FROM shots WHERE id = ?

获取单个镜头的信息。

SELECT COUNT(*) FROM favorites WHERE shot_id = ?

获取将镜头添加到收藏夹的用户计数

SELECT COUNT(*) FROM star WHERE shot_id = ?

获取给予 Star 的用户计数

SELECT COUNT(*) FROM views WHERE shot_id = ?

获取访问此镜头的人数

SELECT AVG(count) AS attention FROM points WHERE shot_id = ? AND date > DATE_SUB(DATE(),INTERVAL 2 DAY) ORDER BY shot_id

当前注意力（最近两天的平均得分）

SELECT SUM(count) AS attention FROM points WHERE shot_id = ? ORDER BY shot_id

镜头的受欢迎程度（自上传镜头以来的点数）

---

以及如何根据关注度和受欢迎程度标准选择镜头（例如，显示所有关注度大于 40 的镜头，或者显示人气大于 100 的镜头）

Answer 1

你的基本需求可以这样完成：-

SELECT s.id,
    s.user_id,
    s.cat_id,
    s.name,
    s.extension,
    s.size,
    s.title,
    s.description,
    s.library,
    s.created,
    s.updated,
    u.username,
    u.fullname,
    c.title AS ctitle,
    c.description AS cdescription,
    COUNT(DISTINCT f.id) AS favorites,
    COUNT(DISTINCT st.id) AS stars,
    COUNT(DISTINCT v.id) AS views
FROM shots s
INNER JOIN users u ON u.id = s.user_id
INNER JOIN categories c ON c.id = s.cat_id
LEFT OUTER JOIN favorites f ON f.shot_id = s.id
LEFT OUTER JOIN stars st ON st.shot_id = s.id
LEFT OUTER JOIN views v ON v.shot_id = s.id
WHERE s.id = 18
GROUP BY s.id,
    s.user_id,
    s.cat_id,
    s.name,
    s.extension,
    s.size,
    s.title,
    s.description,
    s.library,
    s.created,
    s.updated,
    u.username,
    u.fullname,
    ctitle,
    cdescription
ORDER BY s.id

LEFT OUTER JOINs 用于镜头，似乎可能没有收藏夹/星标/视图，并且使用内部连接，其中一个缺失将导致不返回任何记录。

它还使用 COUNT(DISTINCT ...)，因为一个镜头可能有多个收藏夹，因此收藏夹 id 可能会出现多次（这是因为查询获取了可能收藏夹的每个组合，星星和观看次数）。

要添加问题的第二部分，可以通过几个子查询来完成。

如果您要检索许多镜头的详细信息，那么通过加入子查询可能最快：-

SELECT s.id,
    s.user_id,
    s.cat_id,
    s.name,
    s.extension,
    s.size,
    s.title,
    s.description,
    s.library,
    s.created,
    s.updated,
    u.username,
    u.fullname,
    c.title AS ctitle,
    c.description AS cdescription,
    sub_att.current_attention,
    sub_pop.popularity,
    COUNT(DISTINCT f.id) AS favorites,
    COUNT(DISTINCT st.id) AS stars,
    COUNT(DISTINCT v.id) AS views
FROM shots s
INNER JOIN users u ON u.id = s.user_id
INNER JOIN categories c ON c.id = s.cat_id
LEFT OUTER JOIN
(
    SELECT shot_id, AVG(count) AS current_attention 
    FROM points 
    WHERE date > DATE_SUB(DATE(),INTERVAL 2 DAY)
    GROUP BY shot_id
) sub_att ON sub_att.shot_id = s.id
LEFT OUTER JOIN
(
    SELECT shot_id, SUM(count) AS popularity
    FROM points 
    GROUP BY shot_id
) sub_pop ON sub_pop.shot_id = s.id
LEFT OUTER JOIN favorites f ON f.shot_id = s.id
LEFT OUTER JOIN stars st ON st.shot_id = s.id
LEFT OUTER JOIN views v ON v.shot_id = s.id
WHERE s.id = 18
GROUP BY s.id,
    s.user_id,
    s.cat_id,
    s.name,
    s.extension,
    s.size,
    s.title,
    s.description,
    s.library,
    s.created,
    s.updated,
    u.username,
    u.fullname,
    ctitle,
    cdescription,
    sub_att.current_attention,
    sub_pop.popularity
ORDER BY s.id

对于一个单一的镜头，最好将子查询放在语句的 SELECT 部分（这样它会强制为每个返回的行执行一次子查询，这会返回大量记录效率低下）：-

SELECT s.id,
    s.user_id,
    s.cat_id,
    s.name,
    s.extension,
    s.size,
    s.title,
    s.description,
    s.library,
    s.created,
    s.updated,
    u.username,
    u.fullname,
    c.title AS ctitle,
    c.description AS cdescription,
    (
        SELECT AVG(count) AS current_attention 
        FROM points 
        WHERE shot_id = s.id AND date > DATE_SUB(DATE(),INTERVAL 2 DAY)
    ) AS current_attention,
    (
        SELECT SUM(count) AS popularity
        FROM points 
        WHERE shot_id = s.id 
    ) AS popularity,
    COUNT(DISTINCT f.id) AS favorites,
    COUNT(DISTINCT st.id) AS stars,
    COUNT(DISTINCT v.id) AS views
FROM shots s
INNER JOIN users u ON u.id = s.user_id
INNER JOIN categories c ON c.id = s.cat_id
LEFT OUTER JOIN favorites f ON f.shot_id = s.id
LEFT OUTER JOIN stars st ON st.shot_id = s.id
LEFT OUTER JOIN views v ON v.shot_id = s.id
WHERE s.id = 18
GROUP BY s.id,
    s.user_id,
    s.cat_id,
    s.name,
    s.extension,
    s.size,
    s.title,
    s.description,
    s.library,
    s.created,
    s.updated,
    u.username,
    u.fullname,
    ctitle,
    cdescription,
    sub_att.current_attention,
    sub_pop.popularity
ORDER BY s.id