How to query (fetch) a multiple table of mysql database as a single table in codeigniter

问题

I have three database table

1st

vedd_plan_task ::
task_id | task name

2nd

  plan_task_mapping ::
  task_mapp_id | plan_id | task_id

3rd

tbl_plan ::
plan_id | plan_title | plan_price | plan_desc

In this table i mapped the 2nd table with 1st & 3rd. (2 table's value come from 1st & 3rd)

for PLAN i call the data from PLAN TASK tbl. and submit the data in two different table. now i have to show the database as table but i can't find the way to get a task_name form mapping table.

I want a table with this field

Plan_id | plan_title | plan_price | plan_desc | task_name (which i inserted before with particular plan id)..

回答1:

$query = $this->db->query('SELECT tbl_plan.plan_id ,plan_title ,plan_price ,plan_desc ,task_name,plan_task_mapping.task_id FROM tbl_plan LEFT JOIN plan_task_mapping ON plan_task_mapping.plan_id = tbl_plan.plan_id LEFT JOIN vedd_plan_task ON vedd_plan_task.task_id = plan_task_mapping.task_id');

foreach ($query->result() as $row) {    

echo $row->plan_id; 
echo $row->plan_title;
echo $row->plan_price;
echo $row->plan_desc;
echo $row->task_name; 
echo $row->task_id; 

} ?>

回答2:

$this->db->join('vedd_plan_task','vedd_plan_task.task_id=plan_task_mapping.task_id','inner');
$this->db->join('plan_task_mapping ','plan_task_mapping.plan_id=tbl_plan.plan_id ','inner');
$this->db->get('tbl_plan');

回答3:

$this->db->select('tbl_plan.plan_id,tbl_plan.plan_title,tbl_plan.plan_price,tbl_plan.plan_price,tbl_plan.plan_desc,vedd_plan_task.task_name');

$this->db->from('plan_task_mapping,tbl_plan,vedd_plan_task');

$this->db->where('plan_task_mapping.plan_id = tbl_plan.plan_id and plan_task_mapping.task_id=vedd_plan_task.task_id');

$query = $this->db->get();
return $query; 

来源：https://stackoverflow.com/questions/31427631/how-to-query-fetch-a-multiple-table-of-mysql-database-as-a-single-table-in-cod