ID from insert with multiple rows

Is it safe to assume that the auto increment id from a insert with multiple rows will be incremented by one starting to the mysql_last_insert_id() value? Could there be a concurrent insert (from an other user session) between this multiple insert?

In this example tbl_name has an autoincrement field called id:

INSERT INTO tbl_name (a,b,c) VALUES(1,2,3),(4,5,6),(7,8,9);

$nbAffectedRows = mysql_affected_rows();
$idFirstRowInserted = mysql_last_insert_id();

$arrayId = array();
if($nbAffectedRows &a开发者_JS百科mp;gt; 0){
    for($i = 0; $i <= $nbAffectedRows; $i++){
        $arrayId[] = $idFirstRowInserted + $i;
    }
}

Will $arrayId always contain values incremented by one correponding to the 'id' of the rows inserted ?

It will be safe to assume that, if you wrap your INSERTs in a transaction. As a side effect your query will run faster too.