table a:
aid na nb
0 1 2
1 1 3
2 3 2查询结果:
nab
1
2
3结果为字段na和字段nb的记录去除重复后的汇总。
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from (
select na as nab from a
union
select nb as nab fromm a
)T
order by T.nab
Unknown column 'T.nab' in 'field list'
select nab
from (
select na as nab from a
union
select nb as nab fromm a
)T
order by T.nab
select nab
from (
select distinct na as nab from a
union
select distinct nb as nab fromm a
)T
order by T.na
Unknown column 'T.na' in 'order clause'
而且,第一次的那个没有加distinct 也有过滤重复的效果
只是,有没有简单点的?写sql语句和执行都比较麻烦……
from (
select distinct na as nab from a
union
select distinct nb as nab fromm a
)T
order by T.nab
第一个貌似错了吧 第一个的结果集你看了吗
nab
1
2
3
第二个会提示:
Unknown column 'T.na' in 'order clause'