//定义接口
interface DBI<T>{
  add(info:T):boolean
  get(id:number):any[]
}

//定义一个数据库类
class MysqlDb<T> implements DBI<T>{
  add(info:T):boolean{
    console.log(info);
    return true
  }
  get(id:number):any{
    var list = [
      {
        id:1,
        name:'123'
      }
    ]
    return list
  }
}

//定义第二个数据库类
class Mysql<T> implements DBI<T>{
  add(info: T): boolean {
    throw new Error("Method not implemented.");
  }
  get(id: number): any[] {
    throw new Error("Method not implemented.");
  }
}

//定义操作数据
class User {
  username:string | undefined
  password:string | undefined
}

//实例化user
var u = new User()
u.username = '11'
u.password = '222'

//实例化MysqlDb
var Db = new MysqlDb<User>()
Db.add(u)
console.log(Db.get(2));