mysql组合查询

Question

需要帮助，我们如何结合这些查询？香港专业教育学院的一个问题在连接语句..

SELECT hc.id_company, hc.name, hc.email, dc.country, dc.date_join, 
sum(if(ha.type='ADMIN',1,0)) as ADMIN, 
sum(if(length(ha.type)=6,1,0)) as STAFF, 
sum(if(ha.type='CUST',1,0)) as CUST 
from h_company hc, d_company dc 
JOIN h_adminstaffcust ha USING (id_company) 
where hc.id_company=dc.id_company 
group by id_company; 

SELECT max(logs.date) 
FROM h_company hc LEFT JOIN logs ON (hc.id_company = logs.id_company) 
group by hc.id_company 
having max(logs.date)<'2009-08-15'; 

thx2非常重要的帮助.. 最后我修改，以消除先加入的第一个查询。 这里是我的代码结合在一起......

SELECT 
    hc.ID_COMPANY, 
    hc.NAME, 
    hc.email, 
    (SELECT dc.country FROM d_company dc WHERE hc.ID_COMPANY = dc.ID_Company) as country, 
    (SELECT dc.date_join FROM d_company dc WHERE hc.ID_COMPANY = dc.ID_Company) as date_join, 
    max(logs.date), 
    (SELECT COUNT(ha.ID_COMPANY) FROM h_adminstaffcust ha WHERE hc.ID_COMPANY = ha.ID_Company and TYPE = 'ADMIN') as ADMIN, 
    (SELECT COUNT(ha.ID_COMPANY) FROM h_adminstaffcust ha WHERE hc.ID_COMPANY = ha.ID_Company and TYPE = 'CUST') as CUST, 
    (SELECT COUNT(ha.ID_COMPANY) FROM h_adminstaffcust ha WHERE hc.ID_COMPANY = ha.ID_Company and length(TYPE)=6) as STAFF 
    FROM h_company hc LEFT JOIN logs ON (hc.id_company = logs.id_company) 
    GROUP BY hc.ID_COMPANY 
    having max(logs.date)<'2009-08-15'; 

Answer 1

的几种方法，但我不完全知道你在找什么把它们结合起来。如果你正在寻找刚刚返回的有一个最大日志日期小于2009-08-15的公司，你可以使用exists：

SELECT hc.id_company, hc.name, hc.email, dc.country, dc.date_join, 
    sum(if(ha.type='ADMIN',1,0)) as ADMIN, 
    sum(if(length(ha.type)=6,1,0)) as STAFF, 
    sum(if(ha.type='CUST',1,0)) as CUST 
from h_company hc, d_company dc 
JOIN h_adminstaffcust ha USING (id_company) 
where hc.id_company=dc.id_company 
and exists (
    SELECT 1 
    FROM h_company hc1 LEFT JOIN logs ON (hc1.id_company = logs.id_company) 
    where hc1.id_company = hc.id_company 
    group by hc1.id_company 
    having coalesce(max(logs.date), '1900-01-01') < '2009-08-15' 
) 
group by id_company; 

另外请注意，我用coalesce，以确保您捕捉null日志。现在

，如果你想看到的最后一个日志日期：

SELECT hc.id_company, hc.name, hc.email, dc.country, dc.date_join, 
    sum(if(ha.type='ADMIN',1,0)) as ADMIN, 
    sum(if(length(ha.type)=6,1,0)) as STAFF, 
    sum(if(ha.type='CUST',1,0)) as CUST 
from h_company hc, d_company dc 
JOIN h_adminstaffcust ha USING (id_company) 
inner join (SELECT hc1.id_company, max(logs.date) as maxdate 
    FROM h_company hc1 LEFT JOIN logs ON (hc1.id_company = logs.id_company) 
    group by hc1.id_company 
    having coalesce(max(logs.date), '1900-01-01') < '2009-08-15')) as logs on 
    hc.id_company = logs.id_company 
where hc.id_company=dc.id_company 

如果你要的只是一个特定的公司这样做，这样做：

SELECT hc.id_company, hc.name, hc.email, dc.country, dc.date_join, 
    sum(if(ha.type='ADMIN',1,0)) as ADMIN, 
    sum(if(length(ha.type)=6,1,0)) as STAFF, 
    sum(if(ha.type='CUST',1,0)) as CUST 
from h_company hc, d_company dc 
JOIN h_adminstaffcust ha USING (id_company) 
inner join (SELECT hc1.id_company, max(logs.date) as maxdate 
    FROM h_company hc1 LEFT JOIN logs ON (hc1.id_company = logs.id_company) 
    where hc1.id_company = 1245 --Add where clause here 
    group by hc1.id_company 
    having coalesce(max(logs.date), '1900-01-01') < '2009-08-15')) as logs on 
    hc.id_company = logs.id_company 
where hc.id_company=dc.id_company 

这样一来，你不是活得t返回该子查询中的整个列表。