SQL 中多列的成对交集计数

Question

假设我有一个包含多个 table 的 SQL 数据库，并且每个 table 都有一列 code。我想要生成的是 table 显示每对 code 列之间共享的代码数。 IE。成对交集计数图：

       table1 table2 table3 table4
table1     10      2      3      5
table2      2     10      4      1
table3      3      4     10      2
table4      5      1      2     10

我可以使用例如

单独获取每个值

WITH abc AS 
(
SELECT code FROM table1
INTERSECT
SELECT code FROM table2
)

SELECT COUNT(*) AS table1Xtable2 FROM abc

但是是否有一个查询可以根据需要生成整个输出 table？

Answer 1

以下表格得到所有个组合：

select t1, t2, t3, t4, count(*) 
from (select code, max(t1) as t1, max(t2) as t2, max(t3) as t3, max(t4) as t4
      from ((select code, 1 as t1, 0 as t2, 0 as t3, 0 as t4
             from table1
            ) union all
            (select code, 0 as t1, 1 as t2, 0 as t3, 0 as t4
             from table2
            ) union all
            (select code, 0 as t1, 0 as t2, 1 as t3, 0 as t4
             from table3
            ) union all
            (select code, 0 as t1, 0 as t2, 0 as t3, 1 as t4
             from table4
            )
           ) t
      group by code
     ) t
group by t1, t2, t3, t4;

对于您的特定问题，您可以使用：

with t as (
      select code, 'table1' as tablename from table1 union all
      select code, 'table2' as tablename from table2 union all
      select code, 'table3' as tablename from table3 union all
      select code, 'table4' as tablename from table4 
     )
select t1.tablename,
       sum(case when t2.tablename = 'table1' then 1 else 0 end) as t1,
       sum(case when t2.tablename = 'table2' then 1 else 0 end) as t2,
       sum(case when t2.tablename = 'table3' then 1 else 0 end) as t3,
       sum(case when t2.tablename = 'table4' then 1 else 0 end) as t4
from t t1 join
     t t2
on t1.code = t2.code
group by t1.tablename

请注意，上面假设 code 在表中是唯一的。如果重复了，可以把union all换成union.

SQL 中多列的成对交集计数

Pairwise intersection counts of multiple columns in SQL

sql

sql-server

intersection

pairwise