帮忙写个SQL语句

[jianghua008]

sales:
comcode sales
a 5
a 6
b 7
b 8

companyinfo:
comcode name
a sz
b gz

要求输出:
name avgsales
sz 6.5
gz 7.5

[caiyunxia]

select name,avg(sales) from
sales a,companyinfo b where a.comcode=b.comcode
group by name

[spland]

select name,avg(sales) from
sales left join companyinfo on sales.comcode = companyinfo.comcode
group by name sales.comcode

[pengdali]

题目有问题吗？看不出有联系呀！

[pengdali]

如果是要

name avgsales
sz 5.5
gz 7.5

的话：

select b.name,cast(avg(a.sales+0.0) as numeric
(10,1) from sales a,companyinfo b where a.comcode=b.comcode
group by name

[luckhua]

SELECT companyinfo.name,sales.sales
FROM companyinfo
LEFT JOIN
(SELECT comcode,AVG(sales)AS sales
FROM sales
GROUP BY comcode
) AS
sales ON sales.comcode=companyinfo.comcode

[benxie]

select name,avg(sales) from sales a,companyinfo b where a.comcode=b.comcode
group by name

[gawz]

具體的思路是什麼啊...什麼聯繫啊