CodeIgniter-内部联接5个或更多表（SQL）

Question

I have 5 tables and I want to inner join them but my codes doesn't work. Can someone help me? Thanks

$query = $this->db->select('tblmastersection.*, tblsavesection.*,tblmastersecmolecular.*,tblmastersecpathology.*,tblmastersecparasitology.* ')
          ->from('tblmastersection')
          ->join('tblsavesection', 'tblmastersection.section_id = tblsavesection.section_id', 'inner')
           ->join('tblmastersecmolecular', 'tblsavesection.test_id = tblmastersecmolecular.test_id', 'inner')
          ->join('tblmastersecparasitology', 'tblsavesection.test_id = tblmastersecparasitology.test_id', 'inner')
            ->join('tblmastersecpathology', 'tblsavesection.test_id = tblmastersecpathology.test_id', 'inner')
            ->get();
    return $query->result();

Answer 1

I think the problem is in the select call. Query Builder is probably not "escaping" your list of fields correctly which results in an invalid statement.

Since you want all fields from all five tables this should work.

$query = $this->db
    ->select('*')
    ->from('tblmastersection')
    ->join('tblsavesection', 'tblmastersection.section_id=tblsavesection.section_id', 'inner')
    ->join('tblmastersecmolecular', 'tblsavesection.test_id = tblmastersecmolecular.test_id', 'inner')
    ->join('tblmastersecparasitology', 'tblsavesection.test_id = tblmastersecparasitology.test_id', 'inner')
    ->join('tblmastersecpathology', 'tblsavesection.test_id = tblmastersecpathology.test_id', 'inner')
    ->get();

return $query->result();

The above can be made a little bit more concise and still produce the same result. The Query Builder method get() can accept the name of a table. So use

->get('tblmastersection') 

instead of

->from('tblmastersection')
//and later in the chain
->get()

Also, know that if a select() method is not provided then SELECT * is assumed.

Lastly, assigning the return from the chained methods to $query provides no benefit unless you want to check that $query is valid before using it. Since you're not checking $query don't use it. Just go ahead and add ->result() to the chain and return the outcome immediately.

Here's the rewrite using that knowledge.

return $this->db
    ->join('tblsavesection', 'tblmastersection.section_id=tblsavesection.section_id', 'inner')
    ->join('tblmastersecmolecular', 'tblsavesection.test_id = tblmastersecmolecular.test_id', 'inner')
    ->join('tblmastersecparasitology', 'tblsavesection.test_id = tblmastersecparasitology.test_id', 'inner')
    ->join('tblmastersecpathology', 'tblsavesection.test_id = tblmastersecpathology.test_id', 'inner')
    ->get('tblmastersection')
    ->result();