C#Linq语法

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1、

ZKWebForm1219_20171128Entities db = new ZKWebForm1219_20171128Entities();        protected void Button1_Click(object sender, EventArgs e)        {            //where:简单形式=================            var qy = from c in db.city                     where c.name == "武汉市"                     select c;            foreach (var im in qy)            {                //Response.Write(im.name+"====="+im.provinceId+"=====");                //Response.Write("<br />");            }            //筛选            var q = from st in db.LbtProjectInfo                    where st.ID < 600                    select st;            foreach (var item in q)            {                //Response.Write(item.ID+"      "+item.ProjectName+"====="+item.ContractNumber+"=====");                //Response.Write("<br />");            }            //筛选：关系条件形式=================            var qyd = from sct in db.LbtProjectInfo                      where sct.ID > 500 && sct.ID < 550                      select sct;            foreach (var iem in qyd)            {                //Response.Write(iem.ID + "      " + iem.ProjectName + "=====" + iem.ContractNumber + "=====");                //Response.Write("<br />");            }            Response.Write("<br />");            //var qyd2 = db.LbtProjectInfo.Where(p => p.ID > 500).Where(p => p.ID < 550);            var qyd2 = db.LbtProjectInfo.Where(p => p.ID > 500 && p.ID < 550);            foreach (var iem2 in qyd2)            {                //Response.Write(iem2.ID + "      " + iem2.ProjectName + "=====" + iem2.ContractNumber + "=====");                //Response.Write("<br />");            }            //First():形式(返回序列中第一个元素)            LbtProjectInfo  sp=db.LbtProjectInfo.First();            //Response.Write(sp.ID + "      " + sp.ProjectName + "=====" + sp.ContractNumber + "=====");            LbtProjectInfo spw = db.LbtProjectInfo.First(c => c.ID == 547);            //Response.Write(spw.ID + "      " + spw.ProjectName + "=====" + spw.ContractNumber + "=====");        }

 //匿名类型            var qam = from sect in db.LbtProjectInfo                      where sect.ID < 550                      select new { sect.ID, sect.ProjectName };            foreach (var ist in qam)            {                //Response.Write(ist.ID + "      " + ist.ProjectName);                //Response.Write("<br />");            }            //指定类型形式            var qamd = from y in db.LbtProjectInfo                       where y.ID < 550                       select new                       {                           ID = y.ID,                           PN = y.ProjectName                       };

2、拉姆语法：

string[] names = { "Tom", "Dick", "Harry", "Mary", "Jay" };   IEnumerable<string> query2 = names                .Where(n => n.Contains("a"))    //n直接来自names array                .OrderBy(n => n.Length)         //n来自filter之后的subsequent                .Select(n => n.ToUpper());      //n来自OrderBy之后的subsequent

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