视图查询-j9九游

视图查询可以实现不依赖数据库视图的多表查询，并不需要数据库支持视图，例如：

db::view('user','id,name')
    ->view('profile','truename,phone,email','profile.user_id=user.id')
    ->view('score','score','score.user_id=profile.id')
    ->where('score','>',80)
    ->select();

生成的sql语句类似于：

select user.id,user.name,profile.truename,profile.phone,profile.email,score.score from think_user user inner join think_profile profile on profile.user_id=user.id inner join think_socre score on score.user_id=profile.id where score.score > 80

注意，视图查询无需调用table和join方法，并且在调用where和order方法的时候只需要使用字段名而不需要加表名。

默认使用inner join查询，如果需要更改，可以使用：

db::view('user','id,name')
    ->view('profile','truename,phone,email','profile.user_id=user.id','left')
    ->view('score','score','score.user_id=profile.id','right')
    ->where('score','>',80)
    ->select();

生成的sql语句类似于：

select user.id,user.name,profile.truename,profile.phone,profile.email,score.score from think_user user left join think_profile profile on profile.user_id=user.id right join think_socre score on score.user_id=profile.id where score.score > 80

可以使用别名：

db::view('user',['id'=>'uid','name'=>'account'])
    ->view('profile','truename,phone,email','profile.user_id=user.id')
    ->view('score','score','score.user_id=profile.id')
    ->where('score','>',80)
    ->select();

生成的sql语句变成：

select user.id as uid,user.name as account,profile.truename,profile.phone,profile.email,score.score from think_user user inner join think_profile profile on profile.user_id=user.id inner join think_socre score on score.user_id=profile.id where score.score > 80

可以使用数组的方式定义表名以及别名，例如：

db::view(['think_user'=>'member'],['id'=>'uid','name'=>'account'])
    ->view('profile','truename,phone,email','profile.user_id=member.id')
    ->view('score','score','score.user_id=profile.id')
    ->where('score','>',80)
    ->select();

生成的sql语句变成：

select member.id as uid,member.name as account,profile.truename,profile.phone,profile.email,score.score from think