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在读取Student表时inner join Class表取的对应的Class信息: //inner join var query = from s in db.Students join c in db.Classes on s.ClassID equals c.ClassID where c.ClassID == 1 select new { ClassID = s.ClassID, ClassName = c.Cla...

可以用 into 语法,配合 DefaultIfEmpty() 方法加载右侧表中的空值。例子:var query =from r in db.Rolesjoin sr in(from ss in db.StaffInRoleswhere ss.StaffId == staffIdselect ss)on r.Id equals sr.RoleIdinto xfrom y in x.DefaultIfEmp...

IQueryable result = from c in db.GetTable() join t in db.GetTable() on new { id = c.ID, id1 = c.ID } equals new { id = t.ClassID, id1 = id } select new ClassInformation { ID = c.ID, ClassID = t.ClassID, Name = c.Name, TeacherNa...

Linq to Sql:var a=from g in Groupsjoin u in Userson g.Id equals u.GroupIdinto Grpfrom grp in Grp.DefaultIfEmpty()select new { GroupName=g.GroupName, UserName=(grp==null)?"":grp.UserName};var b=from u in Usersjoin g in Groupson ...

我们在做SQL查询的时候经常会用到Inner Join,Left Join,笛卡尔积等等,连接方式的概念方面我想也不用给予太多解释, 我们今天的重点是让大家熟悉LINQ是如何使用Join来实现常用的表连接的。 创建测试用类: class Customer { public int Customer...

.问题解决 通过以上分析,将''改为NULL,问题得到有效解决或者把谓词写到每个子SQL里面。当然,只要是非''的都是可以的,比如' '(空格)。 dingjun123@ORADB> SELECT * 2 FROM (SELECT t1.subobject_name, t1.object_name, t1.object_type 3 FRO...

from A in DFZFORMT055 join B in FM_CODE_LIST on A.MoneyType = B.ITEM_VALUE AND B.FORM_KIND = 'DFZ.FORM.T055' AND B.FIELD_NAME= 'MoneyType' join C in JOIN FM_CODE_LIST on A.PayMentType = C.ITEM_VALUE AND C.FORM_KIND = 'DFZ.FORM....

写个简单的你就懂了 var query = from u in User join d in Department on u.DepID equals d.ID into j from u in j select u.ID,u.Name,d.ID.d.Name; 手写的,没验证能否通过编译,不过大概原理就是这样

var data = from a in Student from b in Student where a.Name == "李博" && a.Sex == b.Sex select b;

您好,我在别的论坛也看到您的问题,我来为您解答: DataTable joinTable= new DataTable(); foreach (DataTable dt in dataTables) { joinTable.Merge(dt); } 希望我的回答对你有帮助。

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