表假设是这样的
t_product
id name
——————————————————
1 p_name_1
2 p_name_2
3 p_name_3
4 p_name_4
t_record
id pid count
————————————————
1 1 5
2 2 5
3 4 40
4 4 45
5 2 2
6 2 1
7 4 35
8 4 20
有两个这样的表，主表t_product（产品表），子表t_record（出库记录表，pid为t_product的外键），我要查主表的数据出来，
顺便把最新的出库记录数量（MAX(ID)）查出来，如果没出库记录，则为空，不影响主表显示
效果如：
pid pname lastClunt
——————————————————
1 p_name_1 5
2 p_name_2 1
3 p_name_3
4 p_name_4 20
这样的情况要怎么写这个SQL
——————————————————
制表符都乱了
------解决方案--------------------
SELECT T1.*, T2.COUNT
FROM T_PRODUCT T1,
(SELECT T1.PID, T1.COUNT
FROM T_RECORD T1,
(SELECT MAX(T.ID) ID, T.PID FROM T_RECORD T GROUP BY T.PID) T2
WHERE T1.ID = T2.ID
AND T1.PID = T2.PID) T2
WHERE T1.ID = T2.PID(+)
------解决方案--------------------
with t_product as
(
select 1 id, 'p_name_1' name
from dual
union
select 2 id, 'p_name_2' name
from dual
union
select 3 id, 'p_name_3' name from dual),
t_record as
(select 1 id, 1 pid, 5 count
from dual
union
select 2 id, 1 pid, 6 count
from dual
union
select 3 id, 2 pid, 7 count from dual)
select a.id, a.name, b.count
from t_product a,
(select pid, max(count) KEEP(DENSE_RANK FIRST ORDER BY id desc) count
from t_record
group by pid) b
where a.id = b.pid(+)