Sql 获取仅在两个表之一中的值

我想获取两个表之一中不可用的记录。假设我有一张桌子，上面有：

100
120
140

和表B，其中：

100
110
130

我想获取出现在两个表中但不同时出现在两个表中的值：

120
140
110
130

---

我可以想出三种方法，可能还有其他方法。我认为这与您尝试的最接近，将您运行的两个单独的查询结合起来：

select num from a
minus select num from b
union all
(
  select num from b
  minus select num from a
);

或者只在每张桌子上敲一次：：

select num
from(
  select num from a
  union all
  select num from b
)
group by num
having count(*) < 2;

这三种方法都会对数据产生相同的结果。演示如何使用CTEs提供您的值：

with a (num) as (
  select 100 from dual
  union all select 120 from dual
  union all select 140 from dual
),
b (num) as (
  select 100 from dual
  union all select 110 from dual
  union all select 130 from dual
)
select coalesce(a_num, b_num) as num
from (
  select a.num a_num, b.num b_num
  from a
  full outer join b on b.num = a.num
)
where a_num is null or b_num is null;

       NUM
----------
       110
       130
       140
       120

---

我在Oracle文档中尝试了两个seprate查询，如表a中的select id减去表b中的select id减去表a中的select id，表b中的select id减去表a中的select id:“编写一个执行外部联接并返回a和b中所有行的查询，如果它们不满足联接条件（完全外部联接），则扩展为NULL。”，使用FROM子句中的完整[OUTER]联接语法。“我只想要任何一个表中都不存在的记录。

with a (num) as (
  select 100 from dual
  union all select 120 from dual
  union all select 140 from dual
),
b (num) as (
  select 100 from dual
  union all select 110 from dual
  union all select 130 from dual
)
select coalesce(a_num, b_num) as num
from (
  select a.num a_num, b.num b_num
  from a
  full outer join b on b.num = a.num
)
where a_num is null or b_num is null;

       NUM
----------
       110
       130
       140
       120