you could do this with client-side javascript functions. In your
aspx definition - for each dropdownlist -- add the attribute
onChange="javascript:DeleteFromOtherLists(this.id);"
Then in the HEAD of your aspx, define a javascript function..
<HEAD>
<script language="javascript">
function DeleteFromOtherLists(sSelectedID) {
}
</script>
</HEAD>
...
In your javascript function, determine which drop-down ID is calling the
function & run a loop on the other
drop downs - looking for
document.getElementById("otherDropDownList").options[document.getElementById
("otherDropDownList").selectedIndex] ==
document.getElementById(sSelectedID).options[document.getElementById(sSelect
edID).selectedIndex]
If it's equal - you can set the other dropDownList's option to null - and
that will take it out of the drop down list...
document.getElementById("otherDropDownList").options[document.getElementById
("otherDropDownList").selectedIndex] = null;