我有一个下面的表格-
User-id | sequence
1 0
1 1
1 2
2 1
3 2
这里0 1和2是用户最大可以拥有的固定序列,现在我想要一个标记为N,其中用户缺少任何序列,否则标记应该为Y。我可以说输出应为-
1 0 Y
1 1 Y
1 2 Y
2 0 N
2 1 Y
2 2 N
3 0 N
3 1 N
3 2 Y
选择不同的user_id,与序列(0,1,2)交叉连接以获得所有用户+序列组合,与表左连接以计算标志
select us.user_id,
us.sequence,
case when t.user_id is null then 'N' else 'Y' end flag
from
(--all user sequence combinations
select u.user_id, s.sequence
from (select distinct user_id from mytable) u
cross join (select stack (3, 0, 1, 2) as sequence) s
) us --all user+sequence
left join mytable t on us.sequence=t.sequence and us.user_id=t.user_id
order by us.user_id, us.sequence;
演示带有数据示例:
with
mytable as ( --use your table instead of this
select stack(5,
1, 0,
1, 1,
1, 2,
2, 1,
3, 2) as (user_id,sequence)
)
select us.user_id,
us.sequence,
case when t.user_id is null then 'N' else 'Y' end flag
from
(--all user sequence combinations
select u.user_id,
s.sequence
from (select distinct user_id from mytable) u
cross join (select stack (3, 0, 1, 2) as sequence) s
) us --all user+sequence
left join mytable t on us.sequence=t.sequence and us.user_id=t.user_id
order by us.user_id, us.sequence;
结果:
user_id sequence flag
1 0 Y
1 1 Y
1 2 Y
2 0 N
2 1 Y
2 2 N
3 0 N
3 1 N
3 2 Y