SQL语句合并，求指点，谢谢

[兽兽]

 $sql='select a.id,nav,title,attr,color,date 
from mall_article a
  where 5 > (select count(*) from mall_article b where nav = a.nav and date > a.date and nav in(79,78,1))
 and nav in(79,78,1) 
order by a.date DESC';

想在上面的语句当中加入

$sql2='SELECT id,title,attr,color FROM mall_article order by rand() limit  5;';

[xuzuning]

本来 where 5 > (select count(*) from mall_article b where nav = a.nav and date > a.date and nav in(79,78,1)) 的目的是分组后每组不超过 5条
你现在并没有分组，就有蛇足之嫌了

select id,nav,title,attr,color,date 
  from mall_article
  where nav in(79,78,1)
  order by rand() limit  5

[兽兽]

引用 1 楼 xuzuning 的回复:

本来 where 5 > (select count(*) from mall_article b where nav = a.nav and date > a.date and nav in(79,78,1)) 的目的是分组后每组不超过 5条 你现在并没有分组，就有蛇足之嫌了

select id,nav,title,attr,color,date 
  from mall_article
  where nav in(79,78,1)
  order by rand() limit  5

这不和第二条一样的意思嘛。 可以分组5条的同时，再随机出5条吗