Benachrichtigung von einzelner Tabelle erhalten und mit mehreren Tabellen verknüpfen und das Ergebnis als einzelnes Array

Question

i wie eine Tabelle

und wählen Sie alle Mitteilungen aus dieser Tabelle und kommen Sie mit unten genannten Tabellen

1. tbl_notice

2. tbl_task

3. tbl_assignment

und ich versuche, Daten aus Tabellen wie

$sql = "select * from(
    (
    SELECT a.refer_id as id ,a.refer_tbl,b.task_name as name FROM tbl_notification as a 
    LEFT JOIN tbl_task as b ON (a.refer_id= b.task_id)ORDER BY a.created_date desc 
    ) UNION 
    (
    SELECT c.refer_id as id ,c.refer_tbl, d.notice_title as name FROM tbl_notification as c 
    LEFT JOIN tbl_notice as d ON (c.refer_id = d.notice_id)ORDER BY c.created_date desc 
    ) UNION 
    ( 
    SELECT e.refer_id as id,e.refer_tbl, f.title as name FROM tbl_notification as e 
    LEFT JOIN tbl_assignment as f ON (e.refer_id = f.assignment_id) ORDER BY e.created_date desc 
    ))"; 
    $query= $this->db->query($sql)->get(); 

das Ergebnis zeigt, das zu holen Daten aus der ersten Tabelle, wo Join (in Fall tbl_task) andere Tbl_notice und Tbl_assignment Details sind NULL Ergebnis Demo wie diese

Bitte helfen Sie mir, dies zu korrigieren .....

Answer 1

Sie eine LEFT (OUTER) Durchführung JOIN, wenn es klingt wie Sie sind eine einfache alte (INNER) JOIN benötigen. Versuchen Sie folgendes:

SELECT a.refer_id as id ,a.refer_tbl,b.task_name as name FROM tbl_notification as a 
JOIN tbl_task as b ON (a.refer_id= b.task_id)ORDER BY a.created_date desc 
UNION 
SELECT c.refer_id as id ,c.refer_tbl, d.notice_title as name FROM tbl_notification as c 
JOIN tbl_notice as d ON (c.refer_id = d.notice_id)ORDER BY c.created_date desc 
UNION 
SELECT e.refer_id as id,e.refer_tbl, f.title as name FROM tbl_notification as e 
JOIN tbl_assignment as f ON (e.refer_id = f.assignment_id) ORDER BY e.created_date desc 

Answer 2

bekam ich die Antwort mit folgenden Code anhängen

select * from (SELECT a.refer_id as id ,a.refer_tbl,a.created_date,b.task_name as name FROM tbl_notification as a JOIN tbl_task as b ON (a.refer_id= b.task_id AND a.refer_tbl="tbl_task") 
      UNION SELECT c.refer_id as id ,c.refer_tbl,c.created_date, d.notice_title as name FROM tbl_notification as c JOIN tbl_notice as d ON (c.refer_id = d.notice_id AND c.refer_tbl="tbl_notice") 
      UNION SELECT e.refer_id as id,e.refer_tbl,e.created_date, f.title as name FROM tbl_notification as e JOIN tbl_assignment as f ON (e.refer_id = f.assignment_id AND e.refer_tbl="tbl_assignment")) tbl_notification ORDER BY `tbl_notification`.`created_date` desc 

Thaks mir geholfen .....