I've been looking at the MVC development model for the past few days, with the EF framework for adding and pruning databases. Now just a little summary.
When you use the EF to manipulate the database, ADO is added first. NET data model, a data context class is added for us, using objects of this class to do anything to the database. Therefore, you need to create a data context object before you can manipulate the database using EF.
Mydatabaseentities mde = new mydatabaseentities ();
1. use EF to add operations to the database
1.1 Create an object that needs to be manipulated (in general, a table is an entity, that is, a class), with the Tblperson table as an example (int id,string name, string sex,nullable<int> Age) where age cannot be the null ID for the primary key, the autogrow type:
Tblperson personadd=new Tblperson ();
Personadd.name = "LSS";
personadd.sex= "Male";
personadd.age=23; ( supplemental Note: Since the Tblperson table specifies that age cannot be null, it must be assigned, which will be reflected in subsequent modifications to the delete operation )
Note here that because the ID is an auto-grow type, you do not need to assign a value to the ID when you add it.
1.2 Tell EF context to add operations to the database
Mde.tblperson. ADD (Personadd);
1.3 Saving changes to the entity to the database
MdE. SaveChanges ()
2. use EF to delete a database
2.1 Similarly create a Tblperson object
Tblperson persondelete =new Tblperson ();
When deleting and modifying the operation, be sure to indicate the primary key ID ( here is the ID, which is the primary key of a table, the table must specify the primary key when using EF to manipulate the table )
//If we use EF to remove ID is 2 of the the record .
persondelete.id=2;
Because age is non-empty, you need to assign an age value to whatever you want.
persondelete.age=23;
2.2.1 Method1 loading Persondelete objects into the EF entity container
Mde.tblPerson.Attach (Tblpersondelete);
2.2.2 tells the context that the delete operation will take place
Mde.tblPerson.Remove (tblpersondelete);
2.2.3 Save the delete operation to the database
MdE. SaveChanges ();
Here the delete operation is done, the second method is described below
2.2.1 Method2 Loads the Persondelete object into the EF entity container and gets the returned entity object
Dbentityentry<tblperson> entrydelete = mde. Entry<tblperson> (Tblpersondelete);
2.2.2 Modifying the state of the entity object in the EF container to delete
entrydelete.state=system.data.entitystate.deleted
2.2.3 to save the deleted entity object
MdE. SaveChanges ();
3. use EF to make modifications to the database
3.1 Creating a Tblperson object
Tblperson tblpersonmodify=new Tblperson ();
You need to specify an ID when making a modification. Suppose we modify the data with ID 3.
tblpersonmodify.id=3;
Indicates the column to be modified if the name of the data with ID 3 is changed to Yzk
Tblpersonmodify.name= "Yzk";
At the same time, we need to assign an age value
tblpersonmodify.age=34;
3.2 Load the Tblpersonmodify object into the EF framework and get the returned entity object
Dnentityentry<tblperson> Entrymodify=mde. Entry<tblperson> (tblpersonmodify);
3.3 Modifying the storage state of an Tblpersonmodify entity object in the EF framework to unmodified
entrymodify.state=system.data.entitystate.unchanged;
3.4 Modify the attributes in the Tblpersonmodify object to true in the framework's entity state ismodified in the EF, indicating that this property requires EF to modify
Entrymodify.property (D=>d.name). Ismodified=true;
3.5 tells the context to save the modified entity object to the database
MdE. SaveChanges ();
4. querying the database using EF (SQO and LINQ)
4.1 Querying a database using Sqo
4.1.1 here produces a lazy load , through the database tools can know that this step does not go to the database query, but the SQL query language is saved
Dbquery<tblperson> dbquery= mde.tblPerson.Where (d=>d.name like "%l%") as dbquery<tblperson>;
4.1.2 When we use the ToList () method, we can only query from the database except for the data
List<tblperson> list=dbquery.tolist ();
4.2 Querying a database using LINQ statements
(from D in Mde.tblperson where D.name like "%l%" select D)
The above section of code return type is iqueryable<tblperson> generic collection
As with the above, you need to call the ToList () method to convert it to a list collection.
Here, using EF to query the database, modify, add, delete operation has been finished, I hope you will be a lot of advice together progress!!! ~~~~
MVC + EF framework to make additions and deletions to databases