根据不同条件分别求和

$balanceMoney = $balanceModel
    ->where(['user_id'=>$v['id']])
    ->field("sum(CASE WHEN type = '17' THEN money ELSE 0 END) as money,

sum(CASE WHEN type = '18' THEN money ELSE 0 END) as money18

")
    ->select()->toArray();