SQL删除只出现一次的数据

[rongguo52013]

删除某字段中只出现一次的数据如
A B C
1 2 3
2 3 4
1 5 6
上面的A字段中2只出现一次，所以要把那条数据数据。改怎么写

[lzp4881]

delete from table as T where (select count(a) from table where A=T.A)=1

[灬上海爽爷]

需要一个标识，比如主键ID，用来区分他们的不同

delete from table t1 where A not in (select A from table where A=t1.A and ID<>t1.ID)

[挨踢直男]

delete from tb where a in (select a from tb as t where (select count(*) from tb where a = t.a)=1)