Linq查询

最新推荐文章于 2023-04-25 11:27:13 发布

转载最新推荐文章于 2023-04-25 11:27:13 发布 · 265 阅读

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原文链接：http://www.cnblogs.com/LYunF/p/3370740.html

本文介绍了SQL中的三种连接查询方式：左连接、右连接和内连接，并通过具体的代码示例展示了如何使用这些连接来操作数据库表。

1、左连接：

var LeftJoin = from emp in ListOfEmployees 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 ListOfEmployees on dept.ID equals employee.DeptID into joinDeptEmp from employee in joinDeptEmp.DefaultIfEmpty() select new { EmployeeName = employee != null ? employee.Name : null, DepartmentName = dept.Name };

3、内连接：

var query = from t in entitiy.TB_GCGL_ADA_USER join p in entitiy.TB_GCGL_ZY_ZYK on t.ETPRS_CODE equals p.ETPRS_CODE

select new TB_USER_ZYK { USER_ID = t.USER_ID, USER_NAME = t.USER_NAME, USER_PASSWORD = t.USER_PASSWORD,

};

转载于:https://www.cnblogs.com/LYunF/p/3370740.html