所有可能的比特組合

Question

假設我有一個表：

id  val 
0  1 
1  2 
2  4 

我找的SQL，將返回我val列是可能的所有的按位組合。因此，作爲一個例子，從上表中我希望以下可能val組合：

1 -- from original table id: 0 
2 -- from original table id: 1 
3 -- combination of id: 0 & 1 
4 -- from original table id: 2 
5 -- combination of id: 0 & 2 
6 -- combination of id: 1 & 2 
7 -- combination of id: 0 & 1 & 2 

Answer 1

這個查詢僅返回總和（VAL）所有組合，您正在尋找可能沒有什麼。如果您正在尋找逐位&你應該使用t.val & cur.val（感謝@Andrew戴頓） （我沒有創建的T臺，而不是我建會動態。你不會需要一個）

with t as 
    (select 0 as id, 1 as val union all 
    select 1 as id, 2 as val union all 
    select 2 as id, 4 as val), 
cur as 
    (select id, val from t union all 
     select t.id, t.val + cur.val from cur join t on cur.id>t.id) 
select val 
    from cur 
order by val 

輸出

val 
1 
2 
3 
4 
5 
6 
7 

如果添加了新的紀錄，VAL = 8，你會得到：

val 
1 
2 
3 
4 
5 
6 
7 
8 
9 
10 
11 
12 
13 
14 
15 

Answer 2

與你的表稱爲aTable - 我想出了這個

CREATE TABLE #combo (z bigint); 

DECLARE @CNT integer; 

SELECT @CNT = COUNT(0) FROM aTable; 

DECLARE @I int; 
SET @I = 0 
WHILE @I < POWER(2, @CNT) 
BEGIN 
    INSERT #combo VALUES(@I); 
    SET @I = @I + 1; 
END 

--select * from #combo; 

;with cte as (select *, row_number() over (order by id) as rn from aTable), 
    combs as (select c1.z,cte.rn, cte.val, POWER(2, cte.rn -1) & c1.z as flag from cte join #combo c1 ON POWER(2, cte.rn -1) & c1.z != 0) 


select *, row_number() over (partition by z order by rn) as lev, val final_val into #perms from combs order by z,rn; 

--select * from #perms; 

DECLARE @depth as integer; 
SET @depth = 2; 



WHILE EXISTS (SELECT 0 FROM #perms WHERE lev = @depth) 
begin 

    UPDATE #perms 
    SET #perms.final_val = p.final_val & #perms.val 
FROM 
    #perms 
INNER JOIN 
    #perms p 
ON 
    p.lev = #perms.lev - 1 AND p.z = #perms.z 

    set @depth = @depth + 1; 

end 

select #perms.z,#perms.final_val from #perms join (SELECT p.z, max(p.lev) maxz FROM #perms p GROUP BY z) DQ ON #perms.lev = dq.maxz and dq.z = #perms.z order by #perms.z; 

DROP TABLE #combo; 
DROP TABLE #perms; 

---

甚至

with t as 
    (select * from atable), 
cur as 
    (select id, val from t union all 
     select t.id, t.val & cur.val from cur join t on cur.id>t.id) 
select id,val 
    from cur 
order by id