LINQ连接两个数据表

如果表2中不存在该行，则将默认设置为0：

var result = from dataRows1 in table1.AsEnumerable()  join dataRows2 in table2.AsEnumerable()  on dataRows1.Field<string>("ID") equals dataRows2.Field<string>("ID") into lj  from r in lj.DefaultIfEmpty()  select dtResult.LoadDataRow(new object[]  {     dataRows1.Field<string>("ID"),     dataRows1.Field<string>("name"),     r == null ? 0 : r.Field<int>("stock")   }, false);

MSDN 源码