Named variables in sql query

Try this one, no time to test right now busy.
You need to pass in the start and end strings for the dates to search.

PHP Code:

$sql = 'SELECT
MONTHNAME (itd.DateOfshippment) AS Month
,COUNT(itm.Name) AS Operations
FROM ImportsMaster itm
INNER JOIN ImportsDetails itd on itm.ID  = itd.IDMSTR
WHERE itd.Market IS NOT NULL
AND itm.Trader LIKE "%TEXT%"
AND itd.DateOfshippment between "{$start}" and "{$end}"
GROUP BY MONTH(itd.DateOfshippment);'; 


Just tested this also , not working either  here is my full code in the model :

Code:

            $sql = 'SELECT
            MONTHNAME (`itd`.`DateOfshippment`) AS `Months`,
            COUNT(`itm`.`Name`) AS `Operations`
            FROM `ImportsMaster` `itm`
            INNER JOIN `ImportsDetails` `itd` on `itm`.`ID`  = `itd`.`IDMSTR`
            WHERE `itd`.`Market` IS NOT NULL
            AND `itm`.`Trader` LIKE "{$trader}"
            AND `itd`.`DateOfshippment` between "{$start}" and "{$end}"
            GROUP BY MONTH(`itd`.`DateOfshippment`)';
            $this->db->query($sql, [
                'start' => $this->input->post('start'),
                'end' => $this->input->post('end'),
                'trader' => $this->input->post('trader')
            ]);

I've tried your suggestions as well as numerous other  ones , the blinded values are not getting replaced
no matter what .
Also the named bindings documentation seems to be referencing a very old version of codeigniter . In the query builder
class I can only find the documentation about bindings which is very different .
Anyway I can't be the only one here with a similar problem , nobody else in here ever wanted to create a dynamic query using
raw sql ? Some other similar queries I've managed to convert to  query builder but this one uses MONTHNAME and COUNT
to return some values which I haven't figure out yet if I can do in a single query as in raw sql.