case when sql语句问题

当ACFLOW_ACCOUNTTYPE='0' AND (ACFLOW_BEFOREAVAILABLE < ACFLOW_AFTERAVAILABLE)的情况下ACFLOW_CHARGEAMOUNT as availableIncomeAmount
这sql语句怎么写？case when不能加as啊。。。

case when ACFLOW_ACCOUNTTYPE='0' AND ACFLOW_BEFOREAVAILABLE < ACFLOW_AFTERAVAILABLE then ACFLOW_CHARGEAMOUNT end as availableIncomeAmount