面对多表的查询,一般都是多表连接后下面再写条件,但是有一种写法可以提升一下EF生成的语句的效率 首先先去查询每一个表,把每一个表对应的条件附加上去,注意:过滤数据最多的条件放在首先位置 var lt = from l in l select l; if (query.CreateDateStart!=null) { l = l .Where(t=> t.CreateDate>= query.CreateDateStart); } if (query.CreateDateEnd != null)
在asp.net mvc 中,常在控制器中预先加载导航属性,以便在视图中能够显示起关联的数据. 如果不预先加载,View中就会无法呈现外键的 关联数据. 会提示EF 错误发生. 一. 模型: public class Department { public int DepartmentID { get; set; } [StringLength(50, MinimumLength = 3),Display(Name="部门名称")] public string Name { get;
join ); pageCount = _db.Orders.Count(); return _db.Orders.OrderByDescending(c=>c.ID).Skip(skip).Take(pageSize) .Join(_db.Income, a => a.ID, b => b.OrderId, (a, b) => new OrdersInComeModel { ID=a.ID, incometype=b.incometype, Amount=a.Amount, Bu
数据源: 1.无into,相当于 inner join var query = from p in context.P join s in context.S on p.PID equals s.PID select new { p.PNAME, s.SNAME }; query.ToList().ForEach(x => { Console.WriteLine("{0} - {1}", x.PNAME, x.SNAME); }); Console.WriteLine("
185. 部门工资前三高的所有员工 LeetCode_MySql_185 题目描述 方法一:使用join on # Write your MySQL query statement below select d.Name as 'Department', e1.Name as 'Employee', Salary from Employee e1 join Department d on e1.DepartmentId = d.Id where 3 >( # 查找工资高于e1.Salary的个数
