linqtosql转载

var query=from c in student  select new {c.number,c.name,c.age};

var query=from c in student select new {学号=c.number,姓名=c.name, 年领=c.age};

var query=from c in student  orderby c.age ascending  select c;  //升序

var query=from c in studeng orderby c.age descending  select c;//降序

var  query=from c in student group c by c.sex into d select new {性别=c.age}; //d为新表，c.sex为分组字段

var query=(from c in dc.student  select new ｛c.place｝).Distinct();//Distinct()的作用是过滤重复的记录。

var query=(from c in dc.student select new {分布地区=c.place}).Distinct();

int count=student.count();

int count=(from c in  student  where c.name=="王明" select c).count();

from c in dc.Student where c.name.Contain(“王”) select c

var query=from c in dc.Student where c.number.Contain(“2009”) select c

Count( )：计算查询结果的行数
Distinct( )：对查询结果的重复行进行筛选
First( )：取得查询结果的第一行
Last( )：取得查询结果的最后一行
Take(n)：取得查询结果的前n行
Skip(n)：略过前n行,从n+1行开始取
Skip(m).Take(n)：从m+1行开始取后面的n行

1、(from c in Stuent where c.id==“00001” select c).First();

studentDataContext dc = new studentDataContext(); 注意：//xxxDataContext需要与.dbml的文件名一致

var query=from c in dc.student select c;

GridView1.DataSource=query;

GridView1.DataBind();

string num = TextBox2.Text.Trim();  //将要更新学号为多少的相关信息
        string name = TextBox3.Text.Trim();//更新的姓名
        int age = Convert.ToInt32(TextBox4.Text.Trim());//Int32整型 //更新的年龄
         StudentDataContext  dc=new StudentDataContext();
        student stu=(from c in dc.student where c.number==num select c).First();//变量，选取第一行。where后根据主键来更新，其他字段不能。即通过获取主键后，来更新其他字段。
        //除过主键不修改外，其他字段都可以修改
        stu.name = name;//将新修改的名字赋值给数据库中的字段名name
        stu.age = age;//修改年龄
        dc.SubmitChanges();//真正的用于修改数据库。
        bind();//一更改，就显示，和及时刷新相同。

 private void bind()

｛

studentDataContext dc = new studentDataContext();
 var query = (from c in dc.student select c);    //全表查询

 GridView1.DataSource = query;
 GridView1.DataBind();

｝

//插入
string num = TextBox1.Text.Trim();
string username = TextBox2.Text.Trim();
string sex = TextBox3.Text.Trim();
string place = TextBox4.Text.Trim();
 int age = Convert.ToInt32(TextBox5.Text.Trim());

student stu = new student();//创建对象
 //赋新值
//主键不能重复
 stu.number = num;
 stu.name = username;
 stu.sex = sex;
 stu.place = place;
 stu.age = age;
 dc.student.InsertOnSubmit(stu);//对表studen表进行插入操作。//注意，该函数必须写正确。
 dc.SubmitChanges();//数据库保存
 bind();//内容和上面的相同

 string num = TextBox6.Text.Trim();
 student stu =(from c in dc.student where c.number == num select c).First();
 dc.student.DeleteOnSubmit(stu);//删除数据库中的字段，具体怎样删除不管，只管调用该函数即可。
 dc.SubmitChanges();
 bind();