MySQL query Filter

Hello Everybody

 

i have a this query

 

Select * from Data Where SiteID=?SiteID and MainSID=?MainSID and AreaID=?AreaID and ContentType=?ContentType and now() >= DisplaySDate And now() < DisplayEDate order by SBID asc"

this query for site main banner then i want to show banner on mainpage when i not input DisplaySDate and DisplayEDate, so how to change this part

now() >= DisplaySDate And now() < DisplayEDate

 

i`m thinking this way but not working = ==

 

if(now() >= DisplaySDate, DisplaySDate = '0000-00-00 00:00:00') And if(now() < DisplayEDate, DisplayEDate='0000-00-00 00:00:00')

 

so you r guys have an any idea for this problem