小编典典

如何在SQL中比较元组组

sql

如何在sql中比较元组组:请考虑以下示例:

TABLE T1
--------
GROUP     VALUE
-----     -----
A         FOO
A         BAR
X         HHH
X         ZOO

TABLE T2
--------
GROUP     VALUE
-----     -----
B         ZOO
C         FOO
C         BAR

我想编写一个sql查询,比较两个表中的值组并报告差异。在所示示例中,表a:((A,FOO),(A,BAR))中的组与组((C,FOO),(C,BAR))相同,即使组名不同。重要的是该组的内容是相同的。最后,查询将报告存在差异:它是(B,ZOO)元组。

RESULT
------
GROUP     VALUE
-----     -----
B         ZOO
X         HHH
X         ZOO

尽管在T1中包含ZOO的组X在T2中具有匹配值:(B,ZOO),但仍不匹配,因为该组还具有(X,HHH)值,该值不属于(B,ZOO)组在T2


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2021-05-16

共1个答案

小编典典

像这样

create table t1 (group_id varchar2(20), value varchar2(20));
create table t2 (group_id varchar2(20), value varchar2(20));

insert into t1 values ('A','FOO');
insert into t1 values ('A','BAR');
insert into t1 values ('X','HHH');
insert into t1 values ('X','ZOO');
insert into t2 values ('C','FOO');
insert into t2 values ('C','BAR');
insert into t2 values ('B','ZOO');


select t1.group_id t1_group,t2.group_id t2_group, 
      --t1.all_val, t2.all_val, 
       case when t1.all_val = t2.all_val then 'match' else 'no match' end coll_match
from 
  (select 'T1' tab_id, group_id, collect(value) all_val, 
          min(value) min_val, max(value) max_val, count(distinct value) cnt_val 
  from t1 group by group_id) t1
full outer join
  (select 'T2' tab_id, group_id, collect(value) all_val, 
          min(value) min_val, max(value) max_val, count(distinct value) cnt_val 
  from t2 group by group_id) t2
on t1.min_val = t2.min_val and t1.max_val = t2.max_val and t1.cnt_val = t2.cnt_val
/

我已经根据每组中不同值的最小值,最大值和数量进行了初步消除,这将有助于处理大型数据集。如果数据集足够小,则可能不需要它们。

那告诉你比赛。您只需要执行一个额外的步骤,即可找到没有匹配项的组

select t1_group
from
(
  select t1.group_id t1_group,t2.group_id t2_group, 
        --t1.all_val, t2.all_val, 
         case when t1.all_val = t2.all_val then 'match' end coll_match
  from 
    (select 'T1' tab_id, group_id, collect(value) all_val
    from t1 group by group_id) t1
  cross join
    (select 'T2' tab_id, group_id, collect(value) all_val
    from t2 group by group_id) t2
)
group by t1_group
having min(coll_match) is null
/

select t2_group
from
(
  select t1.group_id t1_group,t2.group_id t2_group, 
        --t1.all_val, t2.all_val, 
         case when t1.all_val = t2.all_val then 'match' end coll_match
  from 
    (select 'T1' tab_id, group_id, collect(value) all_val
    from t1 group by group_id) t1
  cross join
    (select 'T2' tab_id, group_id, collect(value) all_val
    from t2 group by group_id) t2
)
group by t2_group
having min(coll_match) is null
/
2021-05-16