Question

In my application i have three tables, reservation, patient and sub_unit, i need to take the patient_id from reservation table and query the patient table for patient data,same time i need to take the sub_unit_id from the reservation table and query the sub_unit name from the sub_unit table... i need to put all this data in to an one array in the sequence like patient_id, sub_unit_name, patient_name, address and pass it to the Codeigniter table class to draw a table.

我如何同时问三张表格来询问这些数据? 你们能够帮助我?

Answer 1

Select r.patient_id, s.sub_unit_name, p.patient_name, p.address 
from reservation r, sub_unit s, patient p 
where r.patient_id = p.patient_id and r.sub_unit_id = s.sub_unit_id

Answer 2

采用代号法,可以做到如下:

$this->db->select( r.patient_id, s.sub_unit_name, p.patient_name, p.address );
$this->db->from( reservation r );
$this->db->join( patient p ,  p.id = r.patient_id );
$this->db->join( sub_unit s ,  s.id = r.sub_unit_id );
$query = $this->db->get();


You can check your formed query by -
echo $this->db->_compile_select();exit;

Answer 3

join syntax在Kall非常简单。你们或许会寻找这样的东西:

SELECT   reservation.patient_id, 
         sub_unit.sub_unit_name, 
         patient.patient_name, 
         patient.address
FROM     reservation
JOIN     patient ON (patient.id = reservation.patient_id)
JOIN     sub_unit ON (sub_unit.id = reservation.sub_unit_id);

在MySQL中,缺省是 Inner Join,我认为这是你重新研究的。 http://en.wikipedia.org/wiki/Join_%28SQL%29#Outer_joins”rel=“nofollow”

Answer 4

它在做伪装时,就是说,它喜欢使用《准则》的积极记录。

    function get_data(){
    $sql =  SELECT * FROM visit,patient,sub_unit WHERE visit.patient_patient_id = patient.patient_id AND visit.sub_unit_sub_unit_id = sub_unit.sub_unit_id ;

    $this->db->order_by("reference_number", "desc");
    $query = $this->db->query($sql);
    return $query;
}

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