Question

sql 中如何删除其中一个表中跟另一个表字段内容重复的行？

如果有a,b两个表，都有username和email 这两个字段，请问a表中要根据b表来删除相同的内容，sql语句怎么写呢？
这两个表在不同的数据库里面

Answer 1

delete from a where a.email in (
select a.email from a, b where a.email = b.email and a.username != b.username
)

Answer 2

delete from a where a.email in (
select a.email from a, b where a.email = b.email and a.username != b.username
)