Multiple mysql query in CI - php

Question

There I have some multiple query and want to execute in Codeigniter.
Below are the code I tried.
function seememberfilter($course,$n)
{
$this->load->database();
$sql = array();
$sql[] = "CREATE TEMPORARY TABLE temp1";
$sql[] = "select id,rand, name,lname, email,phone from `member` where course like ('%$course%')";
$sql[] = "CREATE TEMPORARY table temp2";
$sql[] = "select distinct t.id,t.rand, t.name,t.lname, t.email,t.phone, a.quest_id from temp1 t left join assignment a on t.rand= a.rand";
$sql[] = "CREATE TEMPORARY table randid";
$sql[] = "select rand, quest_id from temp2 where quest_id=$n";
$sql[] = "select t.id,t.rand, t.name,t.lname, t.email,t.phone, r.quest_id from temp1 t left join randid r on t.rand= r.rand";
foreach ($sql as $sql_command)
{
if ($debugging == 0)
{
$this->db->query($sql_command);
}
elseif ($debugging == 1)
{
echo $sql_command;
}
}
return $query->result();
}
Above code is in model and below code is in Controller
public function assign(){
$this->load->model("user_model");
$course=$this->input->post('course');
$n=$this->input->post('id');
$data['sel'] = $this->user_model->seememberfilter($course,$n);
$this->load->view('assign',$data);
}
mysql query are executing well in phpmyadmin. I checked it
What I want: I want to execute mysql query in CI successfully .
I am editing this and giving you sql table complete details
DROP TABLE IF EXISTS `member`;
CREATE TABLE IF NOT EXISTS `member` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`rand` varchar(255) NOT NULL,
`email` varchar(255) NOT NULL,
`name` varchar(255) NOT NULL,
`lname` varchar(255) NOT NULL,
`phone` varchar(255) NOT NULL,
`dob` varchar(255) NOT NULL,
`course` text NOT NULL,
`gender` varchar(255) NOT NULL,
`address` varchar(255) NOT NULL,
`city` varchar(255) NOT NULL,
`state` varchar(255) NOT NULL,
`zip` varchar(255) NOT NULL,
`comment` text NOT NULL,
`Aboutme` text NOT NULL,
`dat` varchar(255) NOT NULL,
`tim` varchar(255) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=7 DEFAULT CHARSET=latin1;
INSERT INTO `member` (`id`, `rand`, `email`, `name`, `lname`, `phone`, `dob`, `course`, `gender`, `address`, `city`, `state`, `zip`, `comment`, `Aboutme`, `dat`, `tim`) VALUES
(1, 'jrf20180961828', 'kk122344545#hotmail.com', 'Kishan', 'Yadav', '9717111111', '2018-09-01', 'paper first,Political Science,Philosophy,', 'male', 'Diamond Auto Mobiles', 'Belthara road', 'ballia', '221715', 'Good person.', '', '06-09-2018', '11:24:16pm'),
(2, 'jrf20180914721', 'kk1#gmail.com', 'Rohan', 'Yadav', '9717111111', '2018-09-01', 'paper first,Philosophy,History,', 'male', 'Diamond Auto Mobiles', 'Belthara road', 'ballia', '221715', 'Good Person.', '', '06-09-2018', '11:25:44pm'),
(5, 'jrf20180958284', 'ykishan94612121#gmail.com', 'kiran', 'Singh', '9717111111', '2018-07-07', 'paper first,Political Science,History,', 'female', 'Diamond Auto Mobiles', 'Belthara road', 'ballia', '221715', 'nnbmnm', '', '10-09-2018', '10:11:34pm'),
(4, 'jrf20180932851', 'kk12#gmail.com', 'Pankaj', 'Yadav', '9717111111', '2018-09-01', 'paper first,Philosophy,Psychology,History,', 'male', 'Diamond Auto Mobiles', 'Belthara road', 'ballia', '221715', 'nmbmbn', '', '10-09-2018', '10:10:19pm'),
(6, 'jrf20180929250', 'hjh#gmail.com', 'John', 'Corter', '9717111111', '2018-09-06', 'paper first,History,', 'male', 'Diamond Auto Mobiles', 'Belthara road', 'ballia', '221715', 'sxs', '', '11-09-2018', '12:09:49am');
COMMIT;
And second table is
DROP TABLE IF EXISTS `assignment`;
CREATE TABLE IF NOT EXISTS `assignment` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`rand` varchar(255) NOT NULL,
`course` varchar(255) NOT NULL,
`quest_id` varchar(255) NOT NULL,
`time` varchar(255) NOT NULL,
`date` varchar(255) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=7 DEFAULT CHARSET=latin1;
INSERT INTO `assignment` (`id`, `rand`, `course`, `quest_id`, `time`, `date`) VALUES
(1, 'jrf20180914721', 'paper first', '2', '10:05:48pm', '2018-09-10'),
(2, 'jrf20180961828', 'paper first', '2', '10:06:49pm', '10-09-2018'),
(3, 'jrf20180914721', 'History', '2', '10:08:03pm', '10-09-2018'),
(4, 'jrf20180958284', 'History', '2', '10:12:05pm', '10-09-2018'),
(5, 'jrf20180914721', 'paper first', '1', '10:19:23pm', '10-09-2018'),
(6, 'jrf20180932851', 'History', '3', '12:07:48am', '11-09-2018');
COMMIT;
And my output should be kind of this, I join two table to get this output.
Attached pic of my output
I get this output using above query. Sorry for my english.

Answer 1

After chat in db-fiddle:
select distinct t.id, t.rand, name, lname, email, phone, if(quest_id='2','2',NULL) as quest-id
from `member` t
left join assignment a on t.rand= a.rand
where t.course like '%History%'
and (a.course like '%History%') or a.id is null
Member constrained to course, assignment same course, quest(ion)_id 2 displayed if it was found, otherwise leave the field as NULL.

Answer 2

You can use transaction to separate Query execution
$this->db->trans_start();
$this->db->query('AN SQL QUERY...');
$this->db->query('ANOTHER QUERY...');
$this->db->query('AND YET ANOTHER QUERY...');
$this->db->trans_complete();