Core ef连接数据库

1：添加nuget Microsoft.EntityFrameworkCore.SqlServer

2：在appsettings.json中添加数据库连接语句 

"ConnectionStrings": {
    "SqlServerConnection": "Data Source = Data Source;Initial Catalog = nitial Catalog;User Id = User Id;Password = Password;"
  }

3：定义DBContext文件

    public class SDKDalDBContext: DbContext
    {
        public SDKDalDBContext(DbContextOptions<SDKDalDBContext> options) :base(options)
        {

        }

}

4：注册中间件，在Startup.cs 方法 ConfigureServices 中添加

services.AddDbContextPool<DBContext>(options => options.UseSqlServer(_configuration.GetConnectionString("SqlServerConnection")));

用构造函数的方法注入IConfiguration 以便读取配置文件

public Startup(IConfiguration configuration)
{
       _configuration = configuration;
}