100分求一sql语句

[imho888]

表A

ID   time   data
2    11:15   9
3    11:30  11

表B

ID   time   data
1    11:00  6
2    11:15   5

表C

ID   time   data
2    11:15   8

合并成如下

time    A.data    B.data   C.data 
11:00              6 
11:15    9         5         8
11:30    11        

最好效率能高一点，因为每个表的数据量比较大。
非常感谢

[cyuyanzhiwen]

with t1 as(
select '2' id,'11:15' time,'9' date1 from dual
union
select '3','11:30','11' from dual)
,t2 as( 
select '1' id,'11:00'time,'6' date1 from dual
union
select '2','11:15','5' from dual)
, t3 as
(select '2' id ,'11:15' time,'8' date1 from dual)
select nvl(t2.time,t1.time),t1.date1,t2.date1,t3.date1
from t2 full join t1 on t2.time=t1.time
full join t3 on t2.time=t3.time
order by t2.time;

[小海葵1]

借楼上数据 SELECT NVL(T1.TIME, T2.TIME, T3.TIME), T1.DATE1, T2.DATE1, T3.DATE1 FROM T1 FULL JOIN T2 ON T1.ID = T2.ID FULL JOIN T3 ON T1.ID = T2.ID ORDER BY NVL(T1.TIME, T2.TIME, T3.TIME)

[sych888]

时间列上加索引

[哥眼神纯洁不]

select time,
max(case when c='A' then date else '' end)as A.data,
max(case when c='B' then date else '' end)as B.data,
max(case when c='C' then date else '' end)as C.data
from (
select time,data,'A' as c from A
union all
select time,data,'B' from B
union all
select time,data,'C' from C) a
group by time

[大明湖畔_帅锅]

with t1 as
(
     select 2 c1,'11:15' c2,9 c3 from dual union all
     select 3 c1,'11:30' c2,11 c3 from dual
),t2 as
(
     select 1 c1,'11:00' c2,6 c3 from dual union all
     select 2 c1,'11:15' c2,5 c3 from dual 
),t3 as
(
     select 2 c1,'11:15' c2,8 c3 from dual 
)

select t.c2,t1.c3,t2.c3,t3.c3
from 
(
select t1.c2
from t1 
union 
select t2.c2
from t2
union select t3.c2
from t3
) t left join t1 on t.c2 = t1.c2
    left join t2 on t.c2 = t2.c2
    left join t3 on t.c2 = t3.c2

     c2      c3    c3    c3
---------------------------------------
1	11:00		6	
2	11:15	9	5	8
3	11:30	11		

[vanjayhsu]

select time, max(case when c='A' then date else '' end)as A.data, max(case when c='B' then date else '' end)as B.data, max(case when c='C' then date else '' end)as C.data from ( select time,data,'A' as c from A union allselect time,data,'B' from B union allselect time,data,'C' from C) a group by time

这种方式效率可能高些，具体要看执行计划。。。。

[rabitsky]

全连接，只需要在time字段上加个索引就可以了。

with 
t1 as
( select '2' id, '11:15' time,  '9' data from dual union 
  select '3' id, '11:30' time, '11' data from dual),
t2 as
( select '1' id, '11:00' time,  '6' data from dual union
  select '2' id, '11:15' time,  '5' data from dual), 
t3 as
( select '2' id ,'11:15' time,  '8' data from dual) 

select nvl(t1.time,nvl(t2.time,t3.time)) time, 
       t1.data "A.data", 
       t2.data "B.data", 
       t3.data "C.data"
from t1
full join t2 on t1.time = t2.time
full join t3 on t1.time = t3.time 

[一十七]

引用 2 楼 HJ_daxian 的回复:

with t1 as
(
     select 2 c1,'11:15' c2,9 c3 from dual union all
     select 3 c1,'11:30' c2,11 c3 from dual
),t2 as
(
     select 1 c1,'11:00' c2,6 c3 from dual union all
     select 2 c1,'11:15' c2,5 c3 from dual 
),t3 as
(
     select 2 c1,'11:15' c2,8 c3 from dual 
)

select t.c2,t1.c3,t2.c3,t3.c3
from 
(
select t1.c2
from t1 
union 
select t2.c2
from t2
union select t3.c2
from t3
) t left join t1 on t.c2 = t1.c2
    left join t2 on t.c2 = t2.c2
    left join t3 on t.c2 = t3.c2

     c2      c3    c3    c3
---------------------------------------
1	11:00		6	
2	11:15	9	5	8
3	11:30	11		

++++++1

[hanks_gao]

引用 8 楼 andy_linky 的回复:

把时间值用维度表的键代替...

我觉得这个思路可以！

WITH t0 AS(
    SELECT 1 ID, '11:00' TIME FROM dual
    UNION
    SELECT 2 ID, '11:15' TIME FROM dual
    UNION
    SELECT 3 ID, '11:30' TIME FROM dual
    UNION
    SELECT 4 ID, '11:45' TIME FROM dual
    UNION
    SELECT 5 ID, '12:00' TIME FROM dual
    UNION
    SELECT 6 ID, '12:15' TIME FROM dual     
),
t1 AS(
    SELECT 2 ID,'11:15' TIME,'9' date1 FROM dual
    UNION 
    SELECT 3,'11:30','11' FROM dual
),
t2 AS( 
    SELECT 1 ID,'11:00' TIME,'6' date1 FROM dual
    UNION 
    SELECT 2,'11:15','5' FROM dual
),
t3 AS(
    SELECT '2' ID ,'11:15' TIME,'8' date1 FROM dual
)
SELECT t0.TIME,t1.date1,t2.date1,t3.date1
FROM t0
LEFT JOIN t1 on t0.TIME = t1.TIME
LEFT JOIN t2 ON t0.TIME = t2.TIME
LEFT JOIN t3 ON t0.TIME = t3.TIME
ORDER BY t0.TIME;

[andy_linky]

能否换个思路解决问题啊。使用UNION效率不会高的啊。

[andy_linky]

例如使用第三个字段表示来源表...

[andy_linky]

把时间值用维度表的键代替...

[大明湖畔_帅锅]

3个表会有1个表的time是全的吗 能包括其他2个表的time数据 有的话 就不用union了