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Linq 左右连接

---左连接  (转载)

DataClasses1DataContext db = new DataClasses1DataContext();
var leftJoinSql = from student in db.Student
join book in db.Book on student.ID equals book.StudentID into temp
from tt in temp.DefaultIfEmpty()
select new
{
sname= student.Name,
bname = tt==null?"":tt.Name//这里主要第二个集合有可能为空。需要判断
};

 

---右连接

DataClasses1DataContext db=new DataClasses1DataContext();
var rightJoinSql = from book in db.Book
join stu in db.Student on book.StudentID equals stu.ID into joinTemp
from tmp in joinTemp.DefaultIfEmpty()
select new {
sname=tmp==null?"":tmp.Name,
bname=book.Name

};