SQL查询如何工作JOIN

Question

有查询：

$result = mysql_query("SELECT
  turs.name,
  turs.age,
  city.city,
  turs.email,
  turs.phone,
  sex.sex,
  country.country,
  date.date,
  turs.opus,
  turs.photo,
  DATE_FORMAT(turs.dateob, '%d-%m-%Y') AS dateob
FROM
  sex
  INNER JOIN (
    date
    INNER JOIN (
      country
      INNER JOIN (
        city
        INNER JOIN turs ON city.id_c = turs.city
      ) ON country.id_co = turs.visitcountry
    ) ON date.id_d = turs.date
  ) ON sex.id_s = turs.sex".$strWhere."
GROUP BY turs.id_t
ORDER BY turs.dateob DESC
LIMIT 10",$db);

它有效但有时结果混淆

还有另一个问题：

$result = mysql_query("SELECT turs.*
FROM (SELECT * FROM turs".$strWhere.") turs
ORDER BY turs.dateob DESC
LIMIT 10",$db);

效果很好。但是我应该在哪里将连接INNERJOIN从第一个查询放到第二个查询？