MYSQL下的SQL语句优化

SQL语句如下：
EXPLAIN INSERT into tmptable select * from itemdata_0_high where id in
(
select min(id) from itemdata_0_high
group by auctionId having count(auctionId) > 1
)
or
id in
(
select id from itemdata_0_high group by auctionId having count(auctionId) = 1
);
执行计划结果如下：

目前已经给auctionId加上了索引。不知道为何还是走的全表扫描呢

http://www.jb51.net/article/39221.htm

不走索引是因为你用了count函数

EXPLAIN INSERT into tmptable select * from itemdata_0_high where id in
(
select min(id) from itemdata_0_high
group by auctionId
)

你试试这个语句是否满足你的要求