전체 글 (6) 썸네일형 리스트형 [JavaScript] getElementById vs getElementsByClassName 처음에 getElementById와 getElementsByClassName에 대해 배우고 사용할 때 궁금하던 것이 있다. 왜 getElementByClassName은 없지? 우선 Id는 유일한 식별자이기 때문에 element에 일대일로 매칭되지만, 동일한 class name을 가진 elements가 다수 존재할 수 있기 때문에 이렇게 사용하도록 만들어놓았을 수 있겠구나 하고 받아들였다. 아래 코드에서 두 버튼의 기능은 동일하지만, getElementById가 아니라 getElementsByClassName을 사용하고자 하는 경우 코드를 적을 때 차이가 있다. getElementById는 단 하나의 element가 선택이 되지만 getElementsByClassName는 한 개 이상의 element가 선.. Lesson 1: SQL and Data Modeling for the Web 1. Interacting with a (remote) database Backend developers need to interact with databases on a regular basis in order to manipulate and maintain the models behind their web applications. In this lesson, we'll build a foundational understanding of how those interactions work. This foundational understanding will be essential in later lessons when we get into more advanced concepts related to dat.. [Introduction to SQL and Data Modeling for the Web] Course Overview In this course, you'll learn the skills needed to traverse the stack and develop an entire database-backed web application. By the end of the course, you'll have the fundamentals you need to start building web applications for anything you can think of! (Well, almost anything!) Here are some of the specific core concepts we'll cover: How to do Create, Read, Update, and Delete (CRUD) operations H.. Lesson 2: Relational Data Models Rule 1: The information rule: All information in a relational database is represented explicitly at the logical level and in exactly one way – by values in tables. More information on Codd's 12 Rules can be found here: Wikipedia link Importance of Relational Databases: Standardization of data model: Once your data is transformed into the rows and columns format, your data is standardized and you.. Lesson 1: Introduction to Data Modeling Databases: A database is a structured repository or collection of data that is stored and retrieved electronically for use in applications. Data can be stored, updated, or deleted from a database. Database Management System (DBMS): The software used to access the database by the user and application is the database management system. Check out these few links describing a DBMS in more detail. In.. [Introduction to Data Engineering] Roles of a Data Engineer & Course road-map Q. What do data engineers do? A. Data engineers gather all kinds of data from different sources, process and combine this data, and then store the clean data in a place that can be easily accessed. The goal is to get everything ready so that a data scientist, business analyst, or really anyone at the company can use this data without having to do much wrangling. Data engineers automate this proc.. 이전 1 다음
