How to implement MySQL multi-table joint query in ThinkPHP

How to implement MySQL multi-table joint query in ThinkPHP: First instantiate the model; then use the table() method or join() method to query, for example: [table('sp_user as t1, sp_dept as t2')].

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Create two tables as shown in the figure:

sp_user table:

sp_dept table:

Purpose: Query the name of the department to which it belongs through the dept_id of sp_user, that is, the name in sp_dept.

Native sq method one:

select t1.*,t2.name as deptname from sp_user as t1,sp_dept as t2 where t1.dept_id = t2.id;

Native sq method two:

select t1.*,t2.name as deptname from sp_user as t1 left join sp_dept as t2 on t1.dept_id = t2.id;

The result is the same:

corresponds to ThinkPHP, there are two types The methods table and join are as follows:

    //多表联查(table)
    public function test18() {
        //实例化模型
        $model = M();
        //查询
        $result =$model->field('t1.*, t2.name as deptname')->table('sp_user as t1, sp_dept as t2')
　　　　　　　　　　　　 ->where('t1.dept_id = t2.id')->select();
        dump($result);
    }
    //多表联查(join)
    public function test19() {
        //实例化模型
        $model = M('User');
        //查询
        $result = $model->field('t1.*, t2.name as deptname')->alias('t1')
　　　　　　　　　　　　 ->join('left join sp_dept as t2 on t1.dept_id = t2.id')->select();
        dump($result);
    }

The test results are the same:

## In summary: ThinkPHP performs multi-table joint query It can be realized through table method and join method respectively. Test environment ThinkPHP3.2.3, table prefix sp_

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