table1とtable2をleft joinするサンプル
var record = (from t1 in table1
join t2 in table2
on t1.ID equals t2.ID into tmp
from joinTable in tmp.DefaultIfEmpty()
select new
{
t1.ID,
t1.name,
t2Name = joinTable.name /*nameが被っているので、別名を設定*/
}
);