Codeigniter sql binding - mysql

Question

How do I use Codeigniter SQL Binding if there are two target dates?
Is how I did it below correct?
public function getInvestmentForBorrowing($id, $Interest, $Currency, $Loantime, $target_date, $Risk_category)
{
$query = '
select CASE WHEN (a.amount_financed - a.amount_invested - a.amount_withdrawn) < a.amount_per_borrower
THEN round((a.amount_financed - a.amount_invested - a.amount_withdrawn), 2)
ELSE round((a.amount_per_borrower) , 2)
END AS investable_amount, a.*,
c.IBAN as Return_IBAN, c.BIC as Return_BIC,
i.average_rate
from investment a
inner join userinfo c
on a.Owner = c.Owner and
c.UPDATE_DT is null
inner join exchange_rates i
on a.Currency = i.currency_id and
? between i.effective_dt and i.expiration_dt
where a.ORIG_ID = ? and
a.Interest <= ? and
a.Currency = ? and
a.status = 2 and
a.Loantime >= ? and
a.Available >= ? and
a.Risk <= ? and
a.UPDATE_DT is null
having investable_amount > 0';
$query = $this->db->query($query, array($target_date, $id ,$Interest, $Currency, $Loantime ,$target_date ,$Risk_category));
$result = $query->result();
return $result;
}
Write now the question marks just represent the array so I added two $target_date to the array but not sure if thats the right way to do it.

Answer 1

It appears to be ok according to the codeigniter documentation but i say that without regard to your original SQL being correct or not.
Just make sure that the number of ? match the number of values you are providing and they are in the right order.
One way to sanity check it, apart from just running it, is to place the following command right after you perform the query:
echo $this->db->last_query();
And providing it known data, you can cheat and just hard code some dummy values for testing, take the generated SQL and throw that into something like phpmyadmin and run it the generated SQL against the Database and see if it works with the expected results.
Just a side note regarding your variable naming style. I see you are mixing cases i.e. things like $target_date (all lower case) and $Risk_category (First letter uppercase). Just be aware that on a linux based system case does matter and mixing like that can cause errors. It's a good idea to decide on one and stick with it.