如果任务对象是用户组

<Where>
<And>
<Or>
<Membership Type=’CurrentUserGroups’>
<FieldRef Name=’AssignedTo’ />
</Membership>
<Eq>
<FieldRef Name=’AssignedTo’  LookupId=’TRUE’ />
<Value Type=’Lookup’>123</Value>
</Eq>
</Or>
<Neq>
<FieldRef Name=’Status’ />
<Value Type=’Text’>Completed</Value>
</Neq>
</And>
</Where>

<Where><And><Or><Membership Type="CurrentUserGroups"><FieldRef Name="AssignedTo" /></Membership><Eq><FieldRef Name="AssignedTo"/><Value Type="Integer"><UserID/></Value></Eq></Or><Neq><FieldRef Name="Status" /><Value Type=’Text’>Completed</Value></Neq></And></Where>

 

可以参阅：http://www.cnblogs.com/ceci/archive/2009/03/31/1425908.html