net core依赖注入设置数据库连接

{
"ConnectionStrings": {
    "DianXinMySql": "server=localhost;port=3306;user=root;password=password;database=db_name"
},
"Logging": {
    "LogLevel": {
    "Default": "Information",
    "Microsoft.AspNetCore": "Warning"
    }
},
"AllowedHosts": "*"
}

builder.Services.AddDbContext<TelecomDbContext>(options =>
    options.UseMySQL(builder.Configuration.GetConnectionString("DianXinMySql")));


其他写法：
IConfiguration configuration = new ConfigurationBuilder()
    .AddJsonFile("appsettings.json", true, true)
    .Build();

//IConfiguration configuration = new ConfigurationBuilder().SetBasePath(Environment.CurrentDirectory).AddJsonFile("appsettings.json").Build();  

builder.Services.AddDbContext<TelecomDbContext>(options =>
{
    options.UseMySQL(configuration.GetConnectionString("DianXinMySql"));
});