mysql如何删除重复数据只保留一条(全字段去复)?

没有主键,全字段去重,在不建立临时表的情况下可能做到吗???

select distinct a from ((select 字段1 a from table) union (select 字段2 a from table) union (select 字段3 a from table) union ... )

DELETE
FROM
table a
WHERE
(a.id, a.seq) IN (
SELECT
id,
seq
FROM
table
GROUP BY
id,
seq
HAVING
count(*) > 1
)
AND rowid NOT IN (
SELECT
min(rowid)
FROM
table
GROUP BY
id,
seq
HAVING
count(*) > 1
)