【TP5 ：数据库：查询构造器：链式操作】视图查询

版权声明：本文为ywcmoon原创文章，未经允许不得转载。 https://blog.csdn.net/qq_39251267/article/details/82257604

视图查询

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，可更改

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：

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

使用数组的方式定义表名以及别名：

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_user member
INNER JOIN think_profile PROFILE ON PROFILE .user_id = member.id
INNER JOIN think_socre Score ON Score.user_id = PROFILE .id
WHERE
    Score.score > 80