.ToList();//返回一個集合，包含查到的所有值；

.First();//返回查到的第一條數據，如果查不到會報錯；

.FirstOrDefault();返回查到的第一條數據，差不到返回一個null；

db.Users.InsertOnSubmit();//添加

db.DeleteOrSubmit();//刪除
db.SubmitChanges();//提交修改，增刪改都需要提交；

//修改取到對象之後直接賦值，提交；

//基礎查，把內容放到泛型集合
using(DBDataContext db = new DBDataContext())
{
   List<Users> ulist = db.Users.ToList();
}
 
//模糊差，contains包含
string a = "123";
using(DBDataContext db = new DBDataContext())
{
   List<Users> ulist = db.Users.where(r => r.Ids.Contains(a))ToList();
}
//精確查，
string a = "123";
using(DBDataContext db = new DBDataContext())
{
   List<Users> ulist = db.Users.where(r => r.Ids==a)ToList();
}
 
//添加
Users u = new Users();
u.ids = "1";
u.UserName = "2";
u.password = "3";
using(DBdataContext db = new DBDataTaxt())
{
try
{
    db.Users.InsertOnSubmit(u);
    db.SubmitChanges();
    MessageBox.Show("成功");
}
catch
{
    MessageBox.Show("失敗");
}
}
//修改
string a = "1";
using(DBdataContext db = new DBDataTaxt())
{
 
try
{
    Users u = db.Usres.where(r => r.ids == a).FirstOrDefault();
    u.ids = "3";
    u.UserName = "2";
    u.password = "1";
    db.SubmitChanges();
    MessageBox.Show("成功");
}
catch
{
    MessageBox.Show("失敗");
}
}

//刪除
string a = "1";
using(DBdataContext db = new DBDataTaxt())
{
    List<Users> ulist = db.Users.where(r => r.Ids == a).ToList();
    if(ulist.Count > 0)
    {
        db.DeleteOnSubmit(ulist[0]);
        db.SubmitChanges();
    }
}

LINQ的最簡單的增刪改查寫法