SPSiteDataQuery query = new SPSiteDataQuery();
query.Lists = "<Lists><List ID=\"111111E1-11FF-1AC1-B1FC-EB1CFCB1AB2D\"/><List ID=\"A111111C-1110-11BE-111B-01111111B115\"/></Lists>";
query.Query = "<Where><Gt><FieldRef Name='ID' /><Value Type='Number'>0</Value></Gt></Where>";
query.Webs = "<Webs Scope='SiteCollection' />";
query.ViewFields = "<FieldRef Name='Title' /><FieldRef Name='ID' />";
query.RowLimit = 10;
DataTable dt = web.GetSiteData(query);
lblMessage.Text = dt.Rows.Count.ToString();
gvData.DataSource = dt;
gvData.DataBind();