I'm trying to get data from 3 tables in one query. Those tables are for storing and displaying user messages. Each user can log in and request all his inbox messages. The user id is avaliable from the PHP session and parameter type=1 gets passed in the php request which means the request to show inbox (type=2 would be info messages etc).
First table called email has id, subject, body and date
Second table called email_routing has message_id, sender_email_id, receiver_email_id, basket, type. The message_id refers to id of the message in email table.
Sender and receiver id refers to email ids from the third table that called people_emails. It consist of id(that what sender and receiver email id refer to), internal_user_id (that's what is avaliable from PHP session), email and people_id (each person may have several emails in the contact book so I store people and their emails in separate tables, but this last column if not of our interest here).
So I can figure out how I would do my queries in sequence and just for one row result:
Fist I would get user email id based on his user_id from PHP session:
$X = SELECT `id` from `people_emails` WHERE `internal_user_id`=$_conf[user]->id;
$X is not a proper coding, let's say it is a variable I would eventually get.
Then I can query the email_routing table to all the messages addressed to that user:
$Y = SELECT `message_id`, `sender_email_id`, `receiver_email_id` FROM `email_routing` WHERE `receiver_email_id`=$X[id] and `type`=$_REQUEST[type];
Having list of the message_id's I can now query the email table for the messages content:
$R = SELECT `subject`, `body`, `date` FROM `email` WHERE `id`=$Y[message_id];
Ok, then I need to "translate" the "from" addresses from its id which I got from email_routing table, so it is:
$Z_from = SELECT `email` FROM `people_emails` WHERE `id`=$X[sender_email_id];
I now have all the data for one row. Then I need to put all together which will be
$Z_from + $R[subject] + $R[body] + $R[date]
I need to have it as one list of results which then gets passed to bootstrap datatables plugin for displaying and searching. I can't seem to figure that one out. Please help.
Your queries, reformatted:
$X: SELECT p.id
FROM people_emails p
WHERE p.internal_user_id = $_conf[user]->id;
$Y: SELECT r.message_id
, r.sender_email_id
, r.receiver_email_id
FROM email_routing r
WHERE r.receiver_email_id = $X[id]
AND r.type = $_REQUEST[type];
$R: SELECT e.subject
, e.body
, e.date
FROM email e
WHERE e.id = $Y[message_id];
$F: SELECT s.email
FROM people_emails s
WHERE s.id = $Y[sender_email_id]
To return these columns:
$F + $R[subject] + $R[body] + $R[date]
The queries can be combined like this:
SELECT s.email AS sender_email
, e.subject
, e.body
, e.date
FROM people_emails p
JOIN email_routing r
ON r.receiver_email_id = p.id
AND r.type = $_REQUEST[type]
JOIN email e
ON e.id = r.message_id
JOIN people_emails s
ON s.id = r.sender_email_id
WHERE p.internal_user_id = $_conf[user]->id;
To add the sender full_name from the people table, we can add a join to that table, and add the column to the SELECT list:
$N = SELECT n.full_name
FROM people n
WHERE n.id = (SELECT s.people_id
FROM people_emails s
WHERE s.email = :sender_email
)
We already have :sender_email from the query above, it's the value returned from s.email in the SELECT list, so we can just add a join to the people table:
SELECT s.email AS sender_email
, n.full_name AS sender_full_name
, e.subject
, e.body
, e.date
FROM people_emails p
JOIN email_routing r
ON r.receiver_email_id = p.id
AND r.type = $_REQUEST[type]
JOIN email e
ON e.id = r.message_id
JOIN people_emails s
ON s.id = r.sender_email_id
JOIN people n
ON n.id = s.people_id
WHERE p.internal_user_id = $_conf[user]->id;
(I can't really test this, since I don't have your table definitions or sample data.)