ACCESS的函数IIf语句如何改成SQL的

ACCESS的函数IIf语句怎么改成SQL的
Select Top 1 * From ZN_ad Where IIf(AD_State_radio=1,(now BETWEEN AD_BeginTime and AD_EndTime),-1)=-1 

这名ACCESS语句怎么改成SQL的？

先谢谢了

[解决办法]

SQL code

Select Top 1 * From ZN_ad Where (AD_State_radio=1 and now BETWEEN AD_BeginTime and AD_EndTime) or 1 = 1
[解决办法]
SQL code
Select Top 1 * From ZN_ad Where AD_State_radio=1 and getdate() BETWEEN AD_BeginTime and AD_EndTimeor (not (AD_State_radio=1))