在一下代码中,写入数据库地址、数据库名、用户名、密码
	    {
  "ConnectionStrings": {
    "DbType": "mysql",
    "Connection": "server=localhost;database=TMS;user=root;password=root"
  }
}
	
		 //#region 获取json文件里的配置
            var Configuration = new ConfigurationBuilder()
                .SetBasePath(System.IO.Directory.GetCurrentDirectory())
                .AddJsonFile("appsettings.json").Build();
            var dbType = Configuration["ConnectionStrings:DbType"];
            var connection = Configuration["ConnectionStrings:Connection"];
	
		if (dbType == "sqlserver")
                services.AddDbContext<DB>(options => options.UseSqlServer(connection));
            else if (dbType == "mysql")
                services.AddDbContext<DB>(options => options.UseMySql(connection));
	
		
	
上面代码中既可以联接mysql数据库,也可以连接sqlserver数据库