SQL Server - all possible combinations of Bit columns

问题

I have an empty table with 7 BIT columns (A, B, C, D, E, F, and G). I am looking to populate this table with rows representing all possible combinations of these columns. Ideally there would be no rows containing duplicates of the exact same combinations. Although I am showing 7 columns here, the number of columns could be greater, so the solution should be scalable.

A snippet of the table after being populated would look similar to below:

Ideally this would be based on an INSERT statement, but I am open to a T-SQL Loop solution as well. I have tried using CROSS JOINS, but my limited knowledge has not gotten me very far.

Any help would be greatly appreciated.

回答1:

Use a CTE and CROSS JOIN it with itself 7 times, as in:

with bits as (select 0 as bit union select 1)
select
  row_number() over(
    order by a.bit, b.bit, c.bit, d.bit, e.bit, f.bit, g.bit) as id,
  a.bit, b.bit, c.bit, d.bit, e.bit, f.bit, g.bit
from bits a
cross join bits b
cross join bits c
cross join bits d
cross join bits e
cross join bits f
cross join bits g

回答2:

You can use the following query

;with bits as (select * from (values(0),(1)) as bits(d))
select *
from
    bits as b1,
    bits as b2,
    bits as b3,
    bits as b4,
    bits as b5,
    bits as b6,
    bits as b7

回答3:

You can do it with recursion.

This solution is less performant than the previous one, I know, because it makes all possible permutations

but at least, it has the advantage that it's scalable on the permutation number

declare @mytable as table (s varchar(10))
insert into @mytable values('1'),('0');

with cte as(
select 0 as perm,cast(s as varchar(10)) s from @mytable
union all
select perm+1,cast(t1.s+t2.s as varchar(10)) from cte t1 inner join @mytable t2 on 1=1
where perm <=7)
select * from cte where perm=7 order by s

来源：https://stackoverflow.com/questions/59971453/sql-server-all-possible-combinations-of-bit-columns

标签

sql

sql-server

tsql

combinations

sql-insert