CDBCriteria中SELECT的绑定参数

I'm using Yii CDBCriteria to find records.

I have to put a string value as a custom column in "SELECT" like this:

$criteria = new CDbCriteria;
$criteria->select = array('*, DATE_ADD(createdon, INTERVAL :timezonediff SECOND) as createdon' );       
$criteria->condition = "some_amount > 1000";        
$criteria->params = array(':timezonediff' => "10800");      
$transModel = new TransactionModel;

I'm having a problem where I'm not able to provide the value for ":timezonediff" token in SELECT.

$criteria->params is only working for the tokens in condition but not for SELECT.

I even tried to give an array in $criteria->select, but it didn't work.

Does anyone know if I'm doing something wrong here ?

Thank you all for contributing. I have solved the issue. I was doing a mistake which was causing an error. I was providing this criteria to another object which did not have :timezonediff token.

Parameters for the tokens even in "select" can be binded in $criteria->params smoothly and it will create no error. So technically there will be no error in the code I posted in question.

Try:

$criteria->condition = $main_condition;     
$criteria->params = array(':timezonediff'=>$main_condition);

You can try to get around this through a CDbExpression:

$criteria->select=array(
    '*',
    new CDbExpression('DATE_ADD(`createdon`, INTERVAL :timezonediff SECOND) as createdon',array(
        ':timezonediff'=>10800,
    )),
);