using System.Linq;
1.DataTable 获取列合计
fiel 为列。
1.1无查询条件
var sum = dt.AsEnumerable().Sum(s => s.Field<decimal>(fiel));
1.2有查询条件
var sum = dt.Select(fiel+" is not null").AsEnumerable().Sum(s => s.Field<decimal>(fiel));
2.List 获取对像
List<Player> listPlayers = new List<Player>();
if (listPlayers.Exists(c => c.gms_location == id))
Player p =listPlayers.First(c => c.gms_location == id);
3.List 合计列
3.1 数量
listPlayers.Where(a => a.gms_gign == "警察" &&a.isDie).Count();
3.2.合计列
List<wktype> rows;
var je = rows.Sum(x => x.je);
var cs = rows.Where().Sum(x => x.cs);
public class wktype public string type { get; set; } public Decimal cs { get; set; }
}
4.List排序 检索 遍历
4.1
List<Player> ps = listPlayers.Where(a => a.gms_gign == "警察").OrderBy(a=>a.gms_location).ToList<Player>();//OrderByDescending
foreach(Player p in ps)
}
更新 ： ps .ForEach(x => x.stock=-1)
带条件更新： info.ForEach(x => { if (x.stock == -1) { x.stock = 1; } });
4.2 where p.gms_gign == "警察" select p;
foreach(Player p in ps)
}
List<int> arr = new List<int>() { 1, 2, 3, 4, 5, 6, 7 }; var s = (from v in arr where v > 3 select v).Sum(); var sss = arr.SelectMany<int, string>(a => { return new List<string>() { "a", a.ToString() }; }); MessageBox.Show(s.ToString());
选取一列，去重，转为字符串数组 string[]
var groups = map.listMap.Where(a => a.visible == "1").Select(o => o.mname).Distinct().ToArray();
或其他数组 .Distinct().ToArray();
var groups1 = map.listMap .Select(o => new { a = o.mname,b="aa" }) .ToArray();
ViewBag.groups1 = groups1;
分组转List<string>
var groups1 = map.listMap .GroupBy(a => a.mname)
.Select(o => o.Key);
ViewBag.groups1 = groups1.ToList();
或其他类型
var groups1 = map.listMap .GroupBy(a => a.mname)
.Select(o => new {key =o.Key});
ViewBag.groups1 = groups1.ToList();
4.3 Join
string roles = string.Join(",", chkListRole.CheckedItems.Cast<string>().Select(a=>a.ToString()));
using System.Linq;
1.DataTable 获取列合计
fiel 为列。
1.1无查询条件
var sum = dt.AsEnumerable().Sum(s => s.Field<decimal>(fiel));
1.2有查询条件
var sum = dt.Select(fiel+" is not null").AsEnumerable().Sum(s => s.Field<decimal>(fiel));
2.List 获取对像
List<Player> listPlayers = new List<Player>();
if (listPlayers.Exists(c => c.gms_location == id))
Player p =listPlayers.First(c => c.gms_location == id);
3.List 合计列
3.1 数量
listPlayers.Where(a => a.gms_gign == "警察" &&a.isDie).Count();
3.2.合计列
List<wktype> rows;
var je = rows.Sum(x => x.je);
var cs = rows.Where().Sum(x => x.cs);
public class wktype public string type { get; set; } public Decimal cs { get; set; }
}
4.List排序 检索 遍历
4.1
List<Player> ps = listPlayers.Where(a => a.gms_gign == "警察").OrderBy(a=>a.gms_location).ToList<Player>();//OrderByDescending
foreach(Player p in ps)
}
更新 ： ps .ForEach(x => x.stock=-1)
带条件更新： info.ForEach(x => { if (x.stock == -1) { x.stock = 1; } });
4.2 where p.gms_gign == "警察" select p;
foreach(Player p in ps)
}
List<int> arr = new List<int>() { 1, 2, 3, 4, 5, 6, 7 }; var s = (from v in arr where v > 3 select v).Sum(); var sss = arr.SelectMany<int, string>(a => { return new List<string>() { "a", a.ToString() }; }); MessageBox.Show(s.ToString());
选取一列，去重，转为字符串数组 string[]
var groups = map.listMap.Where(a => a.visible == "1").Select(o => o.mname).Distinct().ToArray();
或其他数组 .Distinct().ToArray();
var groups1 = map.listMap .Select(o => new { a = o.mname,b="aa" }) .ToArray();
ViewBag.groups1 = groups1;
分组转List<string>
var groups1 = map.listMap .GroupBy(a => a.mname)
.Select(o => o.Key);
ViewBag.groups1 = groups1.ToList();
或其他类型
var groups1 = map.listMap .GroupBy(a => a.mname)
.Select(o => new {key =o.Key});
ViewBag.groups1 = groups1.ToList();
4.3 Join
string roles = string.Join(",", chkListRole.CheckedItems.Cast<string>().Select(a=>a.ToString()));
