我们知道在SQL中一共有五种JOIN操作:INNER JOIN、LEFT OUTER JOIN、RIGHT OUTER JOIN、FULL OUTER JOIN、CROSS JOIN 内连接、 Sql: SELECT [t0].[GroupName], [t1].[UserName] FROM [Group] AS [t0] INNER JOIN [User] AS [t1] ON ([t0].[Id]) =[t1].[GroupId] ...
3、右连接(RIGHT JOIN) //Sql: SELECT g.GroupName,u.UserName FROM GroupName g RIGHT JOIN User u ON g.Id = u.GroupId //Linq to Sql: from u in Users join g in Groups on u.GroupId equals g.Id into Grp from grp in Grp.DefaultIfEmpty() select new { GroupName=(grp==null)?"":g...
<Left | Right> [Outer] Join <Right 资料表> On <Join 规则> 语法中的 Outer 是可以省略的, 例如你可以用 Left Join 或是 Right Join, 在本质上, Outer Join 是 inclusive, 叫它做包容性吧! 不同于 Inner Join 的排他性, 因此在 Left Outer Join 的查询结果会包含所有 Left 资料表的资料, 颠倒过来...
join dept in ListOfDepartment on emp.DeptID equals dept.ID into JoinedEmpDept from dept in JoinedEmpDept.DefaultIfEmpty() select new { EmployeeName = emp.Name, DepartmentName = dept != null ? dept.Name : null }; 2、右连接: var RightJoin = from dept in ListOfDepartment join employee in...
1、Join连接查询分类 SQL中常见的连接查询有: left join: 左连接,返回左表中所有的记录以及右表中连接字段相等的记录。 right join: 右连接,返回右表中所有的记录以及左表中连接字段相等的记录。 inner join: 内连接,又叫等值连接,只返回两个表中连接字段相等的行。
normally when we do left or right outer join with sql query then we use left or right keyword to inform sql server that i want left or right join but with linq there is no such keyword used. so how system understand that i am using left or right join ?
上面的例子都是从单个数据库表中获取数据,如果要从多个数据库表中获取数据则需要使用JOIN语句。 ...以下是这些JOIN类型的简要说明: INNER JOIN:只返回在两个表中都有匹配的行。 LEFT OUTER JOIN:返回左侧表中的所有行,以及右侧表中与左侧表匹配的行。...RIGHT OUTER JOIN:返回右侧表中的所有行,以及...
先准备一下测试数据。建一个Person类和Country类,每个Person都有一个Country,通过Person的CountryId属性和Country的Id属性关联。准备用他们两个类搞两个列表,进行Join操作: class Person { public Person(int id, string name, Gender gender, int age, int iQ, int fQ, int countryId) ...
RightJoin Performs a right outer join between two sequences. This method has 4 overloads. RunLengthEncode Run-length encodes a sequence by converting consecutive instances of the same element into aKeyValuePair<T, int>representing the item and its occurrence count. ...
Besides joining two tables, you can also join three or more tables, join self, create left /right outer join, or join using composite keys. Querying With a View Querying with a view is the same as with a table. For example, you can call the view “current product lists” like this:...