php - 将第三个表添加到两个表联接查询

Question

下面的查询工作得很好。它从两个 MySQL 表“comment”和“login”中提取字段。它对表“login”中的“username”等于变量“$profile”的行执行此操作。它还会提取表“comment”中的“loginid”等于也从“login”中提取的“loginid”的行的字段。

我想从名为“submission”的第三个表中提取数据，该表具有以下字段:

submissionid loginid title url displayurl datesubmitted

我想从“提交”中的行中提取字段，其中“loginid”等于已从其他两个表“登录”和“评论”中提取的“loginid”。

我该怎么做？

提前致谢，

约翰

查询:

  $sqlStrc = "SELECT l.username, l.loginid, c.loginid, c.commentid, c.submissionid, c.comment, c.datecommented
               FROM comment AS c
         INNER JOIN login AS l
                 ON c.loginid = l.loginid
              WHERE l.username = '$profile'
           ORDER BY c.datecommented DESC
              LIMIT 10";

Answer 1

SELECT l.username,l.loginid,c.loginid,c.commentid,c.submissionid,c.comment,
c.datecommented,s.submissionid,s.loginid,s.title,s.url,s.displayurl,s.datesubmitted

FROM comment AS c

INNER JOIN login AS l ON c.loginid = l.loginid
INNER JOIN submission AS s ON s.loginid = l.loginid

WHERE l.username = '$profile'

ORDER BY c.datecommented DESC

LIMIT 10