database - Codeigniter PHP: How do I use explode in codeigniter to find between 2 integers -

i have select box choice of "very low", "low", "medium", "high" , "very high" choose between 0-19,20-39 etc 100.

model:

if  ($this->input->post('interest_rating') != "")   {     $range = explode($this->input->post(' ','interest_rating'));     $this->db->where('webinar_event.interest_rating >= ', $range[0]);     $this->db->where('webinar_event.interest_rating <= ', $range[1]); } 

i 2 separate errors
1)

a php error encountered  severity: warning  message: wrong parameter count explode()  filename: models/hp_model.php  line number: 128  database error occurred  error number: 1064   

2)

you have error in sql syntax; check manual corresponds mysql server version right syntax use near 'andwebinar_event.interest_rating<=' @ line 5

select * (`health_professional`) join `webinar_event` on `webinar_event`.`hpid` = `health_professional`.`hpid` `webinar_event`.`interest_rating` >= , `webinar_event`.`interest_rating` <= 

filename: d:\development\pfizerwebinar\web\system\database\db_driver.php

line number: 330

any appreciated, thanks

error number 1

you have give 2 parameters explode() function first 1 must delemeter , second must string explode(delemeter,string)

so explode must $range = explode(' ', $this->input->post('interest_rating')); error number 2

select * (`health_professional`) join `webinar_event` on `webinar_event`.`hpid` = `health_professional`.`hpid` `webinar_event`.`interest_rating` >= 'somevalue' , `webinar_event`.`interest_rating` <= 'somevalue' 

you dont have value associated in query condition