asp.net使用LINQ to SQL連接數(shù)據(jù)庫及SQL操作語句用法分析

from c in Student select c;

from c in Student select c; 
//整表查詢
from c in Student where c.name=="張三" select c;
//查詢姓名為張三的所有信息

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()的作用是過濾重復的記錄。
var query=(from c in dc.student select new {分布地區(qū)=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需要與.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(); //將要更新學號為多少的相關信息
string name = TextBox3.Text.Trim();//更新的姓名
int age = Convert.ToInt32(TextBox4.Text.Trim());//Int32整型 //更新的年齡
StudentDataContext dc=new StudentDataContext();
student stu=(from c in dc.student where c.number==num select c).First();//變量，選取第一行。where后根據(jù)主鍵來更新，其他字段不能。即通過獲取主鍵后，來更新其他字段。
//除過主鍵不修改外，其他字段都可以修改
stu.name = name;//將新修改的名字賦值給數(shù)據(jù)庫中的字段名name
stu.age = age;//修改年齡
dc.SubmitChanges();//真正的用于修改數(shù)據(jù)庫。
bind();//一更改，就顯示，和及時刷新相同。

private void bind()
{
studentDataContext dc = new studentDataContext();
 var query = (from c in dc.student select c); //全表查詢
 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();//創(chuàng)建對象
//賦新值
//主鍵不能重復
stu.number = num;
stu.name = username;
stu.sex = sex;
stu.place = place;
stu.age = age;
dc.student.InsertOnSubmit(stu);
//對表studen表進行插入操作。
//注意，該函數(shù)必須寫正確。
dc.SubmitChanges();//數(shù)據(jù)庫保存
bind();//內(nèi)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);
//刪除數(shù)據(jù)庫中的字段，具體怎樣刪除不管，只管調(diào)用該函數(shù)即可。
dc.SubmitChanges();
bind();