codeigniter join 2 table data

问题:

hi everyone i am new to codeigniter and currently working on a small project in the project i am trying to join two tables and display there data in single table. i looked at the user guide that codeigniter has an i am not sure how this work

$this->db->join();

what table should be first and what id key should be firs. Can someone explain me more in detail about this please use examples if u can. I am trying to join credential table and tblanswers. Tnx for answering.

i have tried to code a function using this example:

$this->db->select('*');
$this->db->from('blogs');
$this->db->join('comments', 'comments.id = blogs.id');

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

EDIT: instead of using join method in codeigniter is it possible to use a simple function to retrieve the two table data separately? all i want is to echo the data from database table on to a html table in my website page to be displayed is it possible to write two get functions to retrieve two tables separately ?

回答1:

It doesn't matter what table is first... Simply:

<?php

$this->db->select('t1.name, t2.something, t3.another')
     ->from('table1 as t1')
     ->where('t1.id', $id)
     ->join('table2 as t2', 't1.id = t2.id', 'LEFT')
     ->join('table3 as t3', 't1.id = t3.id', 'LEFT')
     ->get();
?>

回答2:

$this->db->join('comments', 'comments.id = blogs.id');

With this line you tell: search me inside comments all comments with id equal blogs.id.

Usually is something like that I think:

$this->db->join('comments', 'comments.blogs_id = blogs.id');

You have to insert into your table a field named blogs_id (int value unisgned) because blogs can have more comments. Isn't important the position of first or second value

回答3:

Hi this will work for joining two tables in codeIgnator.

$this->db->select("chat.id,chat.name,chat.email,chat.phone,chat.date,post.post");
      $this->db->from('chat');
      $this->db->join('post', 'chat.id = post.id');
      $query = $this->db->get();

    if($query->num_rows() != 0)
    {
        return $query->result();
    }
    else
    {
        return false;
    }

You can change to the query as you like do trail and error method to get your appropriate results.

回答4:

here is how it works:

1. suppose we have two tables namely student, library.

note: but remember that one of the column should match if you want to use where condition/ here we assume that both tables have std_id column

2. Write the the select query as follows, in the brackets write what are all the things you want

note:write as shown below don't put quotes to each single one put it on whole at once.

*note: suppose we want name, phone_no. from student table and book_name form library table.*

      $this->db->select('name, phone_number, book_name');

3. Now write the from query and write one of the table name(No rule)

     $this->db->from('student');
   

4. Now join this with the another table with join query

     $this->db->join('library', 'students.std_id=library_std_id');
   

5. Now write the where condition that like you want book name form library table where std id=1(in practical you need to fetch this id from view/database)

     $this->db->where('std_id', 1);
     $q= $this->db->get();
   

That's it it's done now you can print and check the result.