Ar Join

I have a join in my Model - getCustomerType()

and in my view i have an active form, which I am creating this

<?= $form->field($model, 'customerType')->dropDownList($items); ?>

But When the page is run, the debug shows there is a weird query being run, it says

SELECT * FROM `CustomerType` WHERE 0=1

But I am not sure why this is going on.

Also I am not displaying a summary, is there any way to prevent it from running a count(*) query, as this is adding to the time it take for the result to return.