batch insert with "on duplicate key update" in mysql just return first primary key

[Huoql]

<insert ... >
    insert into ...
    values 
    <foreach>...</foreach>
    on duplicate key
    update `foo`=values(`foo`) ...
</insert>

when insert multiple new items, only this first item has primary key value in return
like:
{id=1,...},
{id=null,...},
{id=null,...}

[harawata]

That's because the driver (mysql-connector-java) returns only the first generated key in that case.

Multi-row insert ("batch insert" means different thing in JDBC) has several limitations and this is one of them.

[Huoql]

Thank you, but I did some test, and when I perform a multi-row insert without 'on duplicate key update', all iDs of item can returned correctly. Is it because the underlying implementations of the two methods are completely different?

[harawata]

You should be able to find many Q&As related to this topic online.
e.g. https://forums.mysql.com/read.php?39,703493,703493#msg-703493

If you want to know the underlying implementation, you can read the actual source. :)
https://github.com/mysql/mysql-connector-j

[Huoql]

Thank you for your answer.