[migration] code first

[Alice52]

Usage of Migrations

1. create sql in DataBase, and use follow command to generate code

   dotnet ef dbcontext scaffold "Server=T0xx-111\SQLEXPRESS;Database=DATABASE_NAME;User Id=sa; Password=sa" Microsoft.EntityFrameworkCore.SqlServer -f -t TABLE_NAME1 -t TABLE_NAME2 --output-dir Models --context-dir Db --context CustomContext --verbose

2. copy and refine code

   • Model: entity model
   • Configuration: entity create code
   • CustomDbContext: add Models and point out datasource in OnConfiguring

3. add follow code to point out datasource in xxDbContext

   protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
   {
       optionsBuilder.UseSqlServer("Server=192.168.111.xxx;Database=DATABASE_Name;User Id=sa; Password=sa");
   }

4. open TableManagement.DataAccess project and run the follow command to generate Migrations and DB

   dotnet ef migrations add MIGRATION_NAME
   dotnet ef database update 
   # this will generate sql
   dotnet ef migrations script -o Custom_Directory 

explain

1. when we execute migration add command, it will do the follow jobs

   • compare source code to xxSnapshot and generate incremental changes

2. when we execute database update command, it will do the follow jobs

   • get all local incremental changes
   • read data from __EFMigrationsHistory
   • then will execute incremental change one by one if which donot in database table
   • and if __EFMigrationsHistory data is more than local, it will ignore this record

reference

1. https://www.jianshu.com/p/42bbbfa2993f