help to create Yii Criteria

I am newbie to Yii,

can someone pl. help me to write a critearia for this sql.

select centerID, cast(centerID as UNSIGNED) as disCode, tblDistrict.disName from tblRainfallData,tblDistrict where disCode=tblDistrict.discode;

I tried a few ways but no success.

Thanks.

I guess the problem is "cast(centerID as UNSIGNED) as disCode"? If so, try using http://www.yiiframework.com/doc-2.0/yii-db-expression.html