static void Main(string[] args)
{
#region
//int[] comparValue = { 0, 0, 11, 11, 22, 11, 11, 22, 22 };
////方法1--加点！！！！
//var tempV = from c in comparValue group c by c into g select new { value = g.Key, count = g.Count() };
//var v1 = (from v in tempV orderby v.count descending select v.value).First();
//Console.WriteLine(v1.ToString());
////方法2
//var query = (from num in
// (
// from number in comparValue
// group number by number into g
// select new
// {
// number = g.Key,
// cnt = g.Count()
// }
// )
// orderby num.cnt descending
// select num.number).First();
//Console.WriteLine("{0}", query);
////方法3
//var res = from n in comparValue
// group n by n into g
// orderby g.Count() descending
// select g;
//// 分组中第一个组就是重复最多的
//var gr = res.First();
//Console.WriteLine(gr.Key);
#endregion
//1、内连接(join)查询
//Lambda写法
var data = Emp.Join(Dept, e => e.DeptId, d => d.DeptId, (e, d) => new { e, d }).ToList();
//Linq写法
var data2 = (from e in Emp
join d in Dept
on e.DeptId equals d.DeptId
select new { e, d }).ToList();
//2、左(left join )连接查询
//Linq写法
var data3 = (from e in Emp
join d in Dept
on e.DeptId equals d.DeptId into list
from dept in list
select new { e, dept }).ToList();
//Lambda写法
var data4 = Emp.GroupJoin(Dept, e => e.DeptId, d => d.DeptId, (e, d) => new { e, d = d.FirstOrDefault() }).ToList();
//3、交叉(Corss join)连接
//Linq写法
var data5 = (from e in Emp
from d in Dept
select new { e, d }).ToList();
//Lambda写法
var data6 = Emp.SelectMany(emp => Dept.Select(dept => new { emp, dept })).ToList();
Console.ReadKey();
}
