Linq 集成化查询（1）
近一段时间抽空看了一下Linq的知识，学习了一下，也分享给大家，以后使用也方便，用过Linq的程序员可能都感觉到得到，Linq和sql语法简直就一样。所有会SQl的学习LInq就很容易了。
废话少说，首先我们构造一个数据源方便说明代码
Student[] strAry =
{
new Student("张三","男",20),
new Student("张20","女",20),
new Student("张一","男",15),
new Student("张花","女",10),
new Student("张美丽","女",20),
new Student("张坏","男",18),
new Student("张蓝蓝","女",20),
};
1.普通查询语法from a.....in 集合 where .....select a 如果需要对集合进行简单的分组 为 from a in 集合 where 条件 group a by a.属性 排序字段
var query1 = from st in strAry group st by st.strSex;
foreach (var grp in query1)
{
System.Console.WriteLine(grp.Key);
foreach (var val in grp)
{
System.Console.WriteLine("\t{0}", val);
}
}
var query2 = from st in strAry
group st by st.intAge into stuGrp
orderby stuGrp.Key descending
select stuGrp;
foreach (var stg in query2)
{
System.Console.WriteLine("{0}岁学生：", stg.Key);
foreach (var st in stg)
{
System.Console.WriteLine("\t{0}", st);
}
}
2，使用linq同时查询两个集合，其中一个集是另一集合的属性 这里可以使用嵌套查询
Student[] strAry2 =
{
new Student("张三","男",20,new List<Socre>{new Socre("语文",120),new Socre("数学",60),new Socre("英语",55)}),
new Student("张一","男",15,new List<Socre>{new Socre("语文",50),new Socre("数学",50),new Socre("英语",90)}),
new Student("张花","女",10,new List<Socre>{new Socre("语文",80),new Socre("数学",60),new Socre("英语",88)}),
new Student("张美丽","女",20,new List<Socre>{new Socre("语文",30),new Socre("数学",40),new Socre("英语",80)}),
new Student("张坏","男",18,new List<Socre>{new Socre("语文",100),new Socre("数学",60),new Socre("英语",60)}),
new Student("张蓝蓝","女",20,new List<Socre>{new Socre("语文",90),new Socre("数学",30),new Socre("英语",86)}),
};
var query3 = from str in strAry2
from strc in str.Socres
where strc.dblscore > 60
group strc by str.strName;//group 后面的句子是分组形成的数据项
foreach (var stg in query3)
{
System.Console.WriteLine(stg.Key);
foreach (var st in stg)
{
System.Console.WriteLine("\t{0}", st);
}
}