How to create codeigniter query from below sql query? - mysql

Question

I've a query like this which is working fine but I want to create a pure CI query from this. I'm new in CI so can anyone help me to figure out how this can be done or suggest me a reference website or link from where i can get help. Thanks
SELECT
user_des,
IFNULL((sent),0) as sent,
IFNULL((viewed),0) as viewed,
CONCAT(IFNULL(fname_usr,user_des),' ',lname_usr,user_des) as fullname,
IFNULL(sum(duration),0) as totalviewtime,
IFNULL((totalviews),0) as views,
IFNULL(sum(sharedcount),0) as shares,
IFNULL(sum(shared),0) as shared
FROM dem_senddemo
INNER JOIN
(SELECT * FROM dem_demos WHERE id_dem IN (746,943,748) AND customer_dem = '1') as demosfiltered
ON demo_des = id_dem
LEFT JOIN
(
(
Select senddemo_wis, sum(duration) as duration, max(datereceived_wis) as datereceived_wis
FROM
(
select senddemo_wis, invited_wis, sum(IFNULL(duration_fea,0) * IFNULL(percentviewed_wis,0)) as duration, max(datereceived_wis) as datereceived_wis
FROM (sta_views
LEFT JOIN sta_featureswisitavisits as s ON visit_fvi = id_vis
LEFT JOIN
(
(SELECT shortvideovid_fea as videoid_fea, shortvideoduration_fea as duration_fea
FROM dem_features
where shortvideoduration_fea > 0)
UNION
(SELECT longvideovid_fea as videoid_fea, longvideoduration_fea as duration_fea
FROM dem_features
where longvideoduration_fea > 0)
) as x
ON videoid_fea = showedvideo_fvi)
LEFT JOIN
sta_wistia as w ON invited_fvi = invited_wis AND s.showedvideo_fvi = w.mediaid_wis AND wistia_vis = email_wis
WHERE countvisit_wis <> 'N'
GROUP BY invited_wis
) as durfea
GROUP BY senddemo_wis
) UNION
(
SELECT senddemo_wis,sum(IFNULL(mainvideoduration_dem ,0) * IFNULL(percentviewed_wis,0)) as duration, max(datereceived_wis) as datereceived_wis
FROM sta_wistia as w
INNER JOIN
(select *, customer_dem as cuss FROM dem_demos) as demcorp ON demo_wis = id_dem AND mainmessagingvideovid_dem = w.mediaid_wis
LEFT JOIN sta_views ON email_wis = wistia_vis
WHERE customer_dem = 1 AND senddemo_wis > 0 AND countvisit_wis <> 'N'
GROUP BY senddemo_wis
)
) as c ON id_des = senddemo_wis
LEFT JOIN
(
SELECT user_des as user2_des, count(id_vis) as totalviews
FROM sta_views
LEFT JOIN dem_invited ON id_invited = invited_vis
LEFT JOIN dem_senddemo ON id_des = id_senddemo
WHERE NOT ISNULL(id_senddemo) AND countvisit_wis != 'N' AND createdon_des BETWEEN '2015-05-31 00:00:00' AND '2015-06-29 23:59:59' AND demo_des IN (746,943,748)
GROUP BY user_des
) as z ON user_des = user2_des
LEFT JOIN
(
SELECT user_des as user3_des, count(id_des) as sent
FROM dem_senddemo
LEFT JOIN dem_invited ON id_senddemo = id_des
WHERE createdon_des BETWEEN '2015-05-31 00:00:00' AND '2015-06-29 23:59:59' AND demo_des IN (746,943,748) AND first_invited = 'YES'
GROUP BY user_des
) as za ON user_des = user3_des
LEFT JOIN
(
SELECT user_des as user4_des, count(id_vis) as viewed
FROM sta_views LEFT JOIN dem_invited ON id_invited = invited_vis
LEFT JOIN dem_senddemo ON id_des = id_senddemo
WHERE NOT ISNULL(id_senddemo) AND countvisit_wis != 'N' AND createdon_des BETWEEN '2015-05-31 00:00:00' AND '2015-06-29 23:59:59' AND state = 'VIEWED'
AND first_invited = 'YES' AND demo_des IN (746,943,748)
GROUP BY user_des
) as zb ON user_des = user4_des
LEFT JOIN
(
SELECT id_senddemo as iddemdemos2, count(id_senddemo) as shared, allshares as sharedcount
FROM
(
SELECT id_senddemo, count(id_senddemo) as allshares
FROM dem_invited
LEFT JOIN dem_senddemo on id_senddemo = id_des
WHERE first_invited <> 'YES' AND demo_des IN (746,943,748)
GROUP BY id_senddemo
) as x
GROUP BY id_senddemo
) as zc ON iddemdemos2 = id_des
LEFT JOIN
sec_users ON user_des = id_usr
WHERE customer_dem = 1 AND createdon_des BETWEEN '2015-05-31 00:00:00' AND '2015-06-29 23:59:59'
GROUP BY user_des