SPQuery query = new SPQuery();
query.Query = "<OrderBy><FieldRef Name='Modified' Ascending='TRUE'/></OrderBy>" +
"<Where><And>" +
"<Eq><FieldRef Name='status'/><Value Type='Text'>" + DocType + "</Value></Eq>" +
"<Eq><FieldRef Name='Department1'/><Value Type='Lookup'>" + Department + "</Value></Eq>" +
"</And></Where>";
using(SPweb newweb = newsite.open()){
SPlist spl = newweb.list.trygetlist("");
datatable dt = spl.getitem(query).getdatatable();
this is just example