EF Getting Started-crud action

One, EF data query
Let's say we've defined the context:
Private Accountcontext db = new Accountcontext ();

1, [basic query] query all
var users = from U in db. SysUsers
Select U;

Users = db. SysUsers;

2, [conditional query] Join the query conditions
Users = from u in db. SysUsers
where u.username = = "Tom"
Select U;

Users = db. Sysusers.where (U = u.username = = "Tom");

3, [Sorting and paging query]
Users = (from u in db. SysUsers
U.username
Select u). Skip (0). Take (5);

Users = db. Sysusers.orderby (U = u.username). Skip (0). Take (5);

Note: Only sorted to page out

4. [Aggregate query]
Total number of user checks
var num = db. Sysusers.count ();
Check Minimum ID
MiniD = db. Sysusers.min (U = u.id);

Note: Aggregate queries can only be queried by function

5. [Connection query]
var users = from ur in db. Sysuserroles
Join u in db. SysUsers
On Ur. Sysuserid equals u.id
Select ur

Second, EF data Update
Data updates in three steps: Find objects--Update object data--Save changes
Public ActionResult Efupdatedemo ()
{
1. Find the Object
var sysuser = db. Sysusers.firstordefault (U = u.username = = "Tom");

2. Updating Object data
if (sysuser! = null)
{
Sysuser.username = "Tom2";
}

3. Save changes
Db. SaveChanges ();

return View ();
}

Third, EF Data Add/Remove
Similar to update.
Public ActionResult Efaddordeletedemo ()
{
Add to
1. Create a new entity
var newsysuser = new Sysuser ()
{
UserName = "Scott",
Password = "Tiger",
email = "[Email protected]"
};
2. Increase
Db. Sysusers.add (Newsysuser);
3. Save changes
Db. SaveChanges ();

Delete
1. Find the object you want to delete
var delsysuser = db. Sysusers.firstordefault (U = u.username = = "Scott");
2. Delete
if (delsysuser!=null)
{
Db. Sysusers.remove (Delsysuser);
}
3. Save changes
Db. SaveChanges ();

Return View ("Efquerydemo");
}

EF Getting Started-crud action