如何計算同一個表中的名稱之間的關係？

Question

我有一個名爲names的表，其中包含名稱和該名稱的組。

我想統計任何兩個名字在任何組中出現的次數。

表

name | group 
--------+------ 
Renato | 1 
John | 1 
Paul | 1 
Renato | 2 
John | 2 
John | 3 
Paul | 3 

預期結果

name 1 | name 2 |count 
--------+--------+----- 
Renato | John | 2 
Renato | Paul | 1 
John | Renato | 2 
John | Paul | 2 
Paul | Renato | 1 
Paul | John | 2 

我怎樣才能做到這一點？

Answer 1

SELECT n1.name AS "name 1", n2.name AS "name 2", 
    COUNT(*) AS "count" 
FROM "names" AS n1 
JOIN "names" AS n2 
    ON n1.group = n2.group 
WHERE n1.name <> n2.name 
GROUP BY n1.name, n2.name 

Answer 2

SELECT 
    lefttbl.name as name_1, 
    righttbl.name as name_2, 
    count(*) as together_count 
FROM 
    xx AS lefttbl 
    INNER JOIN xx AS righttbl on lefttbl.group=righttbl.group 
WHERE lefttbl.name<>righttbl.name 
GROUP BY name_1,name_2 
; 

給你所需的結構。爲了滿足那些能夠正確識別引用不兼容性但不願糾正它的人，我更新了SQL以消除引號的需要。