asp.net使用LINQ to SQL连接数据库及SQL操作语句用法分析

from c in Student select c;

from c in Student select c; 
//整表查询
from c in Student where c.name=="张三" select c;
//查询姓名为张三的所有信息

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 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 Student select c;

var query=from c in Student select c;
foreach( var x in query)
{ Response.Write(x.toString());}

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.Inserton
Submit(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.Deleteon
Submit(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();