Question

我有一个包含2列的表 - “primary”和“secondary”。此外，还有其他列。以下是一组示例行：

id=1, primary=A, secondary=B, .....
id=2, primary=C, secondary=D, .....
....
.......
id=200, primary=B, secondary=A, .....
id=300, primary=J, secondary=D, .....

我需要一个“GROUP BY”查询，该查询将对主要值和次要值属于同一对值的所有行进行分组，而不管顺序。所以，小组应如下所示：

group=1, nodepair=BA, ....   // (primary=A && secondary=B) OR (primary=B && secondary=A)
group=2, nodepair=JM, ....   // (primary=J && secondary=M) OR (primary=M && secondary=J)

感谢。

Answer 1

你在找这样的东西吗？

select least(primary, secondary)
      ,greatest(primary, secondary)
 from yourtable
group 
   by least(primary, secondary)
     ,greatest(primary, secondary);

无论顺序如何，每个独特的小学/中学组合都会给你一组，即{A，B}与{B，A}相同。

Answer 2

select * from table t1
inner join table t2
on t1.primary = t2.secondary 
and t1.secondary = t2.primary

然后你会得到结果：

id = 1，primary = A，secondary = B，id = 200，primary = B，secondary = A. id = 200，primary = B，secondary = A，id = 1，primary = A，secondary = B

sql“group by”将对应于同一对的行分组

2 个答案: