How to remove extra apostrophe - mysql

Question

I wrote a SQL query to find the desired output for my project. I was working fine with the correct output. But suddenly it started to give error and in the SQL query, there is some additional apoatrophe in. How to resolve it?
I tried to add the query to $this->db->query(); but still no use.
public function getStudentConut($id) {
$this->db->select('students.id')
->from('students')
->join('bp','students.pbp = bp.id','left')
->where(condition 1)
->where(condition 2);
$query1 = $this->db->get_compiled_select();
$this->db->select('students.id')
->from('students')
->join('bp','students.dbp = bp.id','left')
->where(condition 1)
->where(condition 2);
$query2 = $this->db->get_compiled_select();
$this->db->select('COUNT(id) as stud_count')
->from('('.$query1." UNION ALL ".$query2.') X')
->group_by('X.id');
$results = $this->db->get();
return $results->num_rows();
}
It was giving correct count earlier. But without any new changes, it started to give the error.
Now I get error:
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '.id`` WHERE ``bp.some_value`` IS NULL AND ``students.`schoo' at line 2
SELECT COUNT(id) as stud_count FROM (SELECT students.id`` FROM ``students`` LEFT JOIN ``bp`` ON ``students.pbp`` = ``bp.id`` WHERE ``bp..Some other condition.. UNION ALL SELECT students.idFROMstudentsLEFT JOINbpONstudents.dbp=bp.id..some other condition....) X GROUP BYX.id`

Answer 1

I think the issue (at least with the double `) is that CodeIgniter isn't very good with subqueries and such. Basically every time you get the compiled select statement it already has the escape identifiers and then you are putting it in the from statement at the end which will add additional escape identifiers on top of that.
`->from('('.$query1." UNION ALL ".$query2.') X')`
Unfortunately, unlike other methods like set, from doesn't have a 2nd parameter that allows you to set escaping to false (which is what I think you need).
I suggest trying this:
$this->db->_protect_identifiers = FALSE;
$this->db->select('COUNT(id) as stud_count')
->from('('.$query1." UNION ALL ".$query2.') X')
->group_by('X.id');
$results = $this->db->get();
$this->db->_protect_identifiers = TRUE;
and also look in to this: ->where(condition 2); which I'm pretty sure shouldn't compile due to lack of quotes. You probably don't want this escaped so you can do ->where('condition 2', '', false); as per: https://www.codeigniter.com/user_guide/database/query_builder.html#CI_DB_query_builder::where
When all else fails, just know that CodeIgniter has some limitations with "advanced" queries and that maybe you should write it out manually as a string utilizing $this->db->escape_str(...) for escaping user input vars, and $this->db->query(...) to run the SQL.