Php – join 3 tables in thesql codeigniter

codeigniterjoin;MySQLPHP

I have 3 tables in my database :-

tbl_roles(role_id,role_name);
tbl_users(id,role_id,username,email,password);
tbl_tickets_replies(id,ticket_id,user_id,role_id,comments)

role_id, id, id are primary keys of corresponding tables.
i need :-

username from tbl_users.
role_name from tbl_roles.
comments from tbl_tickets

where ticket_id from tbl_tickets_replies = $ticket_id coming as a parameter.

My Model Function is :-

function fetch_comments($ticket_id){
        $this->db->select('tbl_tickets_replies.comments,tbl_users.username,tbl_roles.role_name');
        $this->db->where('tbl_tickets_replies.ticket_id',$ticket_id);
        $this->db->from('tbl_tickets_replies');
        $this->db->join('tbl_users','tbl_users.id = tbl_tickets_replies.user_id');
        $this->db->join('tbl_roles','tbl_roles.role_id=tbl_tickets_replies.role_id');
        $comments = $this->db->get('tbl_tickets_replies');
        return $comments;
     }

this is showing database error i.e., I am doing wrong query.
I want to ask how can I join three tables to fetch data from 3 different tables

This error is showing :-

A Database Error Occurred
Error Number: 1066

Not unique table/alias: 'tbl_tickets_replies'

SELECT tbl_tickets_replies.comments, tbl_users.username,
tbl_roles.role_name FROM (tbl_tickets_replies,
tbl_tickets_replies) JOIN tbl_users ON tbl_users.id =
tbl_tickets_replies.user_id JOIN tbl_roles ON
tbl_roles.role_id=tbl_tickets_replies.role_id WHERE
tbl_tickets_replies.ticket_id = '6'

Filename: C:\wamp\www\local.helpdesk.com\bonfire\codeigniter\database\DB_driver.php

Line Number: 330`

Best Answer

You are referring to tbl_tickets_replies twice. Try this:

function fetch_comments($ticket_id){
    $this->db->select('tbl_tickets_replies.comments, 
           tbl_users.username,tbl_roles.role_name');
    $this->db->where('tbl_tickets_replies.ticket_id',$ticket_id);
    $this->db->join('tbl_users','tbl_users.id = tbl_tickets_replies.user_id');
    $this->db->join('tbl_roles','tbl_roles.role_id=tbl_tickets_replies.role_id');
    return $this->db->get('tbl_tickets_replies');
}

Related Solutions

Sql – the difference between “INNER JOIN” and “OUTER JOIN”

Assuming you're joining on columns with no duplicates, which is a very common case:

An inner join of A and B gives the result of A intersect B, i.e. the inner part of a Venn diagram intersection.
An outer join of A and B gives the results of A union B, i.e. the outer parts of a Venn diagram union.

Examples

Suppose you have two tables, with a single column each, and data as follows:

Note that (1,2) are unique to A, (3,4) are common, and (5,6) are unique to B.

Inner join

An inner join using either of the equivalent queries gives the intersection of the two tables, i.e. the two rows they have in common.

select * from a INNER JOIN b on a.a = b.b;
select a.*, b.*  from a,b where a.a = b.b;

a | b
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3 | 3
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Left outer join

A left outer join will give all rows in A, plus any common rows in B.

select * from a LEFT OUTER JOIN b on a.a = b.b;
select a.*, b.*  from a,b where a.a = b.b(+);

a |  b
--+-----
1 | null
2 | null
3 |    3
4 |    4

Right outer join

A right outer join will give all rows in B, plus any common rows in A.

select * from a RIGHT OUTER JOIN b on a.a = b.b;
select a.*, b.*  from a,b where a.a(+) = b.b;

a    |  b
-----+----
3    |  3
4    |  4
null |  5
null |  6

Full outer join

A full outer join will give you the union of A and B, i.e. all the rows in A and all the rows in B. If something in A doesn't have a corresponding datum in B, then the B portion is null, and vice versa.

select * from a FULL OUTER JOIN b on a.a = b.b;

 a   |  b
-----+-----
   1 | null
   2 | null
   3 |    3
   4 |    4
null |    6
null |    5

Mysql – Should I use the datetime or timestamp data type in MySQL

Timestamps in MySQL are generally used to track changes to records, and are often updated every time the record is changed. If you want to store a specific value you should use a datetime field.

If you meant that you want to decide between using a UNIX timestamp or a native MySQL datetime field, go with the native format. You can do calculations within MySQL that way ("SELECT DATE_ADD(my_datetime, INTERVAL 1 DAY)") and it is simple to change the format of the value to a UNIX timestamp ("SELECT UNIX_TIMESTAMP(my_datetime)") when you query the record if you want to operate on it with PHP.

Best Answer

Related Solutions

Sql – the difference between “INNER JOIN” and “OUTER JOIN”

Mysql – Should I use the datetime or timestamp data type in MySQL

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