Automatic database structure update under Code First (Automatic migrations)

Example Web. config

<?XML version= "1.0" encoding= "Utf-8"?><Configuration><configsections><SectionName= "EntityFramework"Type= "System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, version=4.3.0.0, culture= Neutral, publickeytoken=b77a5c561934e089 "/></configsections><System.Web><CompilationDebug= "true"TargetFramework= "4.0"/></System.Web><ConnectionStrings><!--Persist Security info needs to be set to True to save password information because database.setinitializer<mycontext> (new Dropcreatedatabaseifmodelchanges<mycontext> ()); You need to connect to the master library when judging if Code first is consistent with the database structure--  <add name= "MyConnection "providerName = "System.Data.SqlClient"  ConnectionString= "server=.; database=mydb;uid=sa;pwd=111111; Persist Security info=true " /> </connectionStrings></configuration  >               

Product.cs

UsingSystem;UsingSystem.Collections.Generic;UsingSystem.Linq;Usingsystem.web;UsingSystem.ComponentModel.DataAnnotations;NamespaceEF43. updateschema{[Table ("Product")]PublicClassProduct {[Key] [databasegenerated (databasegeneratedoption.identity)]public int ProductId {get; set;} [Required] [Column ( "productname "varchar" )] public string Name {get; set;} /* in order to test Automatic migrations You can release this comment and add-migration The corresponding code for the structure migration will be generated automatically public double price {get; set;} */}}         

MyContext.cs

UsingSystem;UsingSystem.Collections.Generic;UsingSystem.Linq;Usingsystem.web;UsingSystem.Data.Entity;namespace EF43. updateschema{// Create a Context to inherit from DbContext public class Mycontext:dbcontext {// Specify the database connection as: MyConnection public Mycontext (): base (" myconnection ") {} public dbset<product> Products {get; set         

Demo.aspx.cs

/* * Download Entity Framework 4.3 * with nuget * For instructions on automatically updating the database structure under Code first (Automatic migrations): * Note: The package M required through NuGet Anager Console Input Related command * * After updating the entity structure, enter the following command * 1, enable-migrations * Start the migration function, will be generated under the project root directory Migrations folder, there will usually be two files * 1 . Configuration.cs-related configurations, such as whether automatic migration is required (false by default), etc. * 2. 201202290715581_initialcreate.cs-the data structure before migration, the first half is timestamp * * 2, Add-migration-startupprojectname EF43 * Adds a move in the specified project  Move point, this command will require the input of a name parameter, the value of this parameter is the migration point name * Assuming that the input migration names called Myfirsttest will generate a file similar to the following 201202290718442_mytestfirst.cs, which contains two methods up () and down (), respectively, for the upgrade and demotion of this migration point * * 3, Update-database-startupprojectname EF43 (Upgrade the database structure of the specified project to the latest) * Update-database-tar Getmigration: "201202290718442_mytestfirst", upgrade the current database structure to this migration point (no parameter-targetmigration is upgraded to the latest) * Update-database-script, Displays the relevant SQL code for updating the database structure * update-database-script-sourcemigration: "AAA"-targetmigration: "BBB", which displays the migration point "AAA" up/down to the migration point "BBB "The relevant SQL code * Note: If" System.Reflection.TargetInvocationException:Exception has been tHrown by the target of an invocation "exception, see if the project name specified is displayed (this example is-startupprojectname EF43)  */UsingSystem;UsingSystem.Collections.Generic;UsingSystem.Linq;Usingsystem.web;UsingSystem.Web.UI;UsingSystem.Web.UI.WebControls;UsingSystem.Data.Entity;NamespaceEF43. updateschema{PublicPartialClassDemo:System.Web.UI.Page {Protectedvoid Page_Load (Object sender, EventArgs e) {using (var db = new Mycontext ()) {Random random = new Random (); var product = new product {Name = " windows  "+ random. Next ()}; Db. Products.add (product); int recordsAffected = db. SaveChanges (); Response.Write ( " The number of rows that affect the database:  "+ recordsaffected.tostring ());}}}    

Migrations/configuration.cs

NamespaceEF43. migrations{UsingSystem;UsingSystem.Data.Entity;UsingSystem.Data.Entity.Migrations;UsingSystem.Linq;InternalSealedClass configuration:dbmigrationsconfiguration<ef43. Updateschema.mycontext>{PublicConfiguration () {//The database structure is not automatically migrated by default, and there are many other related settings, see dbmigrationsconfiguration<tcontext> automaticmigrationsenabled =False; }ProtectedOverridevoidSeed (EF43. Updateschema.mycontext context) {//This method is called after migrating to the latest version.//You can use the dbset<t>. AddOrUpdate () Helper extension method //To avoid creating duplicate seed data. e.g. ////  context. People.addorupdate ( // p = p.fullname, // new Person {FullName = "Andrew Peters"}, // New person {FullName = ' Brice Lambson '}, // new Person {FullName = "Rowan Miller"} // ); // } }}

Migrations/201202290715581_initialcreate.cs

NamespaceEF43. migrations{UsingSystem.Data.Entity.Migrations;PublicPartialClassinitialcreate:dbmigration {PublicOverridevoidUp () {createtable ( "product" new {ProductId = C.int (nullable: Span style= "COLOR: #0000ff" >false, Identity: truefalse, Unicode: false< Span style= "color: #000000"),}). PrimaryKey (t => T.productid);} public override void down () {droptable ( "product "); } }} 

Migrations/201202290718442_mytestfirst.cs

NamespaceEF43. migrations{UsingSystem.Data.Entity.Migrations;PublicPartialClassmytestfirst:dbmigration {PublicOverridevoidUp () {//AddColumn ("Product", "price", C = c.double (Nullable:false));//Automatically generated code as above, below is my custom, to set the default value of the new field// There are many other related settings that look at Dbmigration addcolumn ("Product", "price", C = + c.double (nullable: false, defaultvalue:10d)); } public override void down () {Dropcolumn ("Product", "price") ; } }} 

Update database structure automatically under Code first (Automatic migrations)