Hibernate双向关联插入数据时候的怪问题

简单描述一下表结构：主表Team，从表Player，建立外键关联。以下是HBM文件：

Team：<hibernate-mapping></hibernate-mapping>

Transaction tx = session.beginTransaction();    
    
        for(int i=0;i<2;i++) {    
    
            Team team = new Team();    
    
            team.setId("Team" + new Integer(i).toString());    
    
            team.setName(team.getId());    
    
            Set
    <player></player>
     players = new HashSet
    <player></player>
    ();    
    
            for(int j=0;j<10;j++) {    
    
                Player player = new Player();    
    
                player.setId("Player" + team.getId()+"."+new Integer(j).toString());    
    
                player.setName(player.getId());    
    
                player.setBirthday(new Date());    
    
                player.setGender(true);    
    
                player.setTeam(team);    
    
                players.add(player);    
    
            }    
    
            team.setPlayers(players);    
    
            session.save(team);    
    
        }    
    
        tx.commit();  

执行代码，SQL打印如下：

Hibernate: select player_.id, player_.team as team1_, player_.name as name1_, player_.gender as gender1_, player_.birthday as birthday1_ from hibernatedemo.player player_ where player_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:selectplayer_.id,player_.teamasteam1_,player_.nameasname1_,player_.genderasgender1_,player_.birthdayasbirthday1_fromhibernatedemo.playerplayer_whereplayer_.id=?

Hibernate:insertintohibernatedemo.team(name,id)values(?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.team(name,id)values(?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate:insertintohibernatedemo.player(team,name,gender,birthday,id)values(?,?,?,?,?)

Hibernate: insert into hibernatedemo.player (team, name, gender, birthday, id) values (?, ?, ?, ?, ?)

问题是：为什么在insert语句之前，会执行select语句，对player进行查询呢？请指教