c# 左连接写法

var itemandformulas =

                     from i in AttendanceItemList

                     join f in AttendanceFormulaList

                     on i.AttendanceCode equals f.ItemCode into itemandformula

                     from formula in itemandformula.DefaultIfEmpty()

                     select new

                     {

                         i.IsShouldSpent,

                         i.InUse,

                         i.AttendanceCode,

                         formula,

                     };

                foreach (var attenitem in itemandformulas)

                {


                     attenitem.formula 为第二个list里的 内容

                }

AttendanceItemList left  join AttendanceItemList on  i.AttendanceCode =f.ItemCode into itemandformula

join 链接

foreach (var update in AttendanceItemList.Join(AttendanceFormulaList,

                         (l) => { return l.AttenceCode; },

                         (e) => { return e.ItemCode; },

                         (l, e) => new { l, e }))

                    {

                    }

可以下载一个 linqpad学习一下.

http://www.cnblogs.com/Mayvar/archive/2011/07/04/wanghonghua_201107040534.html