3d--Knowledge point 1

Three-tier architecture

1.DAL (data access Layer)--correlate with database to make database deletions
2.BLL (business logic Layer)--responsible for subtraction and/or non-operation, such as: User registration
3.ui/web (Presentation layer)

sqlserver<--->dal<-"data"-->bll<--"Data"->ui/web

The data set above is called "Model".
The backend is concentrated in DAL,BLL and partial ui/web, with the front end being Html/css/js

Capture. Pngweb the difference between the front-end css--class and the ID selector

same point: can be applied to any element
Different points:
1.The ID selector can only be used once in a document . Unlike class selectors, an ID selector can only be used once, and only once, in an HTML document. The class selector can be used more than once.
2 . You can use the class selector word list method to set multiple styles for an element at the same time. we can set multiple styles for one element at the same time, but only with the method of the class selector, the ID selector is not possible (the list of ID words cannot be used).

Javascript

1. Declaring variables, unified call Var
2.function name (parameter name) {return variable}
3.for (Var i=0;i<5;i++) {}

JS function

1. Control Document
2. Transfer data (JS transmits data to the back end via Ajax)
3. Do not use. NET server controls because their interpretation is extremely inefficient
4.ajax front-end No refresh display
5.json is a format for transmitting data, key-value pair format {"Key": "Value"} [{},{}]
Ajax transmits data back to the JSON data format, and the backend transmits data in a JSON-formatted forward segment
6.XML basically does not use it to transfer data, but it also uses it to store data

3d--Knowledge point 1