Is there a way to remove comma/s in my database? Codeigniter PHP

Solution:

To remove the extraneous commas going into the database, you can use array_filter, trim, or preg_replace depending on your preference.

With a theoretical value for $this->input->post('coresubjs[]') of

array(
   '',
   '',
   '0',
   'A',
   'B',
   '',
   'D',
   '',
   '',
);

Using implode(',') only will result in

,,0,A,B,,D,,

Disclaimer

However please keep in mind, that any commas in the post values will not be properly accounted for and should be escaped using another means. eg: 1,000 will be exploded as array("1", "000"). For this reason I recommend refactoring in favor of using {-code-10} and json_decode() or serialize() and unserialize(), instead of implode(',') and explode(',')

Example: https://3v4l.org/I2ObY

array_filter

Removes the "empty" values (0, "", false, null) from the implode array argument. This will work against any input value that is empty, including the middle of the array.

implode(',', array_filter($this->input->post('coresubjs[]')))

Result
Notice that all extraneous commas and the 0 value was removed

A,B,D

To circumvent the issue with "empty" values such as 0, false, you can use a custom callback instead.

implode(',', array_filter($this->input->post('coresubjs[]'), function($value) {
    return null !== $value && '' !== $value;
}))

Result
Notice all extraneous commas were removed

0,A,B,D

trim

Removes only the leading and trailing commas from the implode value.

trim(implode(',', $this->input->post('coresubjs[]')), ',')

Result
Notice the leading and trailing commas are removed but extra comma in the middle remained.

0,A,B,,D

preg_replace

Similar to trim, removing the leading and trailing commas from the implode value, with the addition of replacing any 2 or more commas in the middle with a single comma.

preg_replace(['/,{2,}/', '/^,+/', '/,+$/'], [',', '', ''], implode(',', $this->input->post('coresubjs[]')))

Pattern Explanation:

,{2,} any 2 or more commas
^,+ begins with 1 or more comma
,+$ ends with 1 ore more comma

Result
Notice All extraneous commas have been removed

0,A,B,D

Answer

Solution:

In your update_core function, you need to trim the additional ','. You can do this as follow -

public function update_core(){
        $data = array(
            'core_subjects' => rtrim(implode(',', $this->input->post('coresubjs[]')), ','); // remove the extra ',' to the right
        );

        $this->db->where('id', $this->input->post('coresubjID'));
        return $this->db->update('subjects', $data);
}

Also, remember that you don't have to remove the data every time you update. When updating it will automatically overwrite the previous value. So your remove_core method is redundant and should be removed

Source