Question

我能够从 2个表中join信息，以便输出哪些用户说明了哪个状态。它设法从tbl_status获取用户状态，并从tbl_users获取用户的用户名。

但是现在我还要添加用户照片以及状态更新，并在同一查询中输出该信息。毫不奇怪，用户照片包含在tbl_photos。

中

如何将此附加查询添加到现有输出中以使用上一个查询输出结果？

$result = mysql_query("SELECT tbl_status.id as statID, tbl_status.from_user as statFROM, tbl_status.status as statSTATUS, tbl_status.deleted as statDEL, tbl_status.date as statDATE, tbl_users.id as usrID, tbl_users.name as usrNAME FROM tbl_status INNER JOIN tbl_users ON tbl_status.from_user = tbl_users.id WHERE tbl_status.deleted = '0'");

Answer 1

我添加了一个左连接，以防用户没有照片或可选。

SELECT  tbl_status.id AS statID ,
            tbl_status.from_user AS statFROM ,
            tbl_status.status AS statSTATUS ,
            tbl_status.deleted AS statDEL ,
            tbl_status.date AS statDATE ,
            tbl_users.id AS usrID ,
            tbl_users.name AS usrNAME,
            p.photo
    FROM    tbl_status
            INNER JOIN tbl_users ON tbl_status.from_user = tbl_users.id
            Left JOIN tbl_photos p ON tbl_users.id = tbl_photos.userId
    WHERE   tbl_status.deleted = '0'

但是，如果每个用户都有照片，请使用...

SELECT  tbl_status.id AS statID ,
        tbl_status.from_user AS statFROM ,
        tbl_status.status AS statSTATUS ,
        tbl_status.deleted AS statDEL ,
        tbl_status.date AS statDATE ,
        tbl_users.id AS usrID ,
        tbl_users.name AS usrNAME,
        p.photo
FROM    tbl_status
        INNER JOIN tbl_users ON tbl_status.from_user = tbl_users.id
        INNER JOIN tbl_photos p ON tbl_users.id = tbl_photos.userId
WHERE   tbl_status.deleted = '0'

你也没有指定FK是什么，所以我只提了一个tbl_users.id = tbl_photos.userId，你需要将这一行和你从tbl_photo表中提取的字段替换为我使用p.photo

Answer 2

你会扩展

FROM tbl_status INNER JOIN tbl_users ON tbl_status.from_user = tbl_users.id

到

FROM tbl_status INNER JOIN tbl_users ON tbl_status.from_user = tbl_users.id
     INNER JOIN tbl_photo ON tbl_photo.user_id = tbl_users.id

连接的结果被视为一个表，其中两个表的所有列在SQL中彼此相邻，因此可以在另一个JOIN的任一侧使用。

Answer 3

您需要做的只是JOIN表上的另一个tbl_photos。

我必须对tbl_photos做一些假设。

SELECT <all your existing columns>, ISNULL(tbl_photos.profile_filename, 'Default Filename') as ProfilePic
FROM tbl_status
INNER JOIN tbl_users ON tbl_status.from_user = tbl_users.id
LEFT JOIN tbl_photos ON tbl_photos.user_id = tbl_users.id
WHERE tbl_status.deleted = '0'

加入2个以上的表以循环结果

3 个答案: