请问个mysql两表关联问题
我有两表 company 与order，order中有company的外键，company_id,现在做两表联查，要求查出某时间段内的全部company的订单，如果订单数量为0则显示零。语句如下：
select c.id,c.name,c.code,sum(c.id)
from company c left join order d on c.id=d.company_id
where d.gmt_created>"2012-06-01"
and d.gmt_created<"2012-07-01"
and (d.status_bcsticket in(2,4) or d.status_issueticket =5)（这个是查询条件）
group by c.id
想要的结果是这样的：
id name code sum
001 a公司 00a 20
002 b公司 00b 0
003 c公司 00c 0
004 e公司 00e 10
但现在只能显示出这样：
id name code sum
001 a公司 00a 20
大家有办法吗,谢谢指教，急用。
[解决办法]
select c.id,c.name,c.code,sum(c.id) from company c left join order d on c.id=d.company_idand d.gmt_created>"2012-06-01" and d.gmt_created<"2012-07-01" and (d.status_bcsticket in(2,4) or d.status_issueticket =5)（这个是查询条件）group by c.id
