Question

我无法加入此查询。这是我做了什么以及我希望做什么的一个例子（当然，期望的结果不是我得到的）。

14-02-31 02实际为to_char(a_date,'YY-MM-DD hh24')。

--describe are the same
sql> desc tab1

 Name              Null?    Type
 ----------------- -------- --------------------------------------------------------
 a_date                       DATE
 NAME                       VARCHAR2(20)

select * from tab1;
a_date          number
-----           -------
14-02-31 03     12
14-02-31 04     22
14-02-31 05     32
14-02-31 06     42

select * from tab2;
a_date          number
-----           -------
14-02-31 02     21
14-02-31 03     22
14-02-31 06     23
14-02-31 07     24

select * from tab3;
a_date          number
-----           -------
14-02-31 01     121
14-02-31 03     222
14-02-31 05     323
14-02-31 07     424


select a_date,t1.number,t2.number,t3.number
from (select * from tab1) t1,
     (select * from tab2) t2,
     (select * from tab3) t3
where t1.a_date=t2.a_date or
      t1.a_date=t3.a_date or
      t2.a_date=t3.a_date or
      t1.a_date is null or
      t2.a_date is null

期望的结果：

a_date          t1.number     t2.number     t3.number       
-----           -------         -------         -------
14-02-31 01                                     121
14-02-31 02                     21
14-02-31 03     12              22              222
14-02-31 04     22
14-02-31 05     32                              323
14-02-31 06     42              23
14-02-31 07                     24              424

Answer 1

我想你想要一个full outer join：

select coalesce(t1.a_date, t2.a_date, t3.a_date) as a_date, t1.number, t2.number, t3.number
from tab1 t1 full outer join
     tab2 t2
     on t2.a_date = t1.a_date full outer join
     tab3 t3
     on t3.a_date = coalesce(t1.a_date, t2.a_date);

Answer 2

select t1.a_date,t1.number,t2.number,t3.number
from  tab1 t1 left outer join on t1.a_date=t2.a_date
     tab2 t2 left outer join  on t1.a_date=t3.a_date
     tab3 t3  left outer join  on t2.a_date=t3.a_date
where t1.a_date=t2.a_date or
      t1.a_date=t3.a_date or
      t2.a_date=t3.a_date or
      t1.a_date is null or
      t2.a_date is null

加入具有相似日期的行

2 个答案: