[review JS] to consolidate the foundation day23- front end, you should also know some databases

This is my participation 8 The fourth of the yuegengwen challenge 23 God , Check out the activity details ：8 Yuegengwen challenge

*** What I learned today : ( Understand database related issues ) ! Check for defects and make up for omissions ! ***

It can be used as a learning route for beginners , Please refer to , Learning progress is not particularly in a hurry ! Ongoing update

Combine your own understanding , Simple and comprehensive summary in vernacular JavaScript Basic knowledge points in the learning process , Facilitate deeper understanding !

Let's start today's study ! ' Only by laying a solid foundation can we build a tall building '! come on. ! take sth. seriously !!

1、 database

database ： A warehouse for storing data   U disc   Hard disk  

Common database languages ：

• sqlServer
• mysql
• oracle
• db2

The data stored in the database are structured data .

for example ：

Hello everyone , My name is XXX I graduated from Tsinghua University   Computer science   I don't have a girlfriend right now   Welcome to be good friends with you .

full name	Gender	Current address	Graduation school	major
So and so	male	Beijing	tsinghua	Computer
So and so	male	Beijing	Peking University	Communication engineering

structured ：

Data in the database It exists in the form of tables

Relational database : Each database consists of multiple tables , A table consists of multiple rows and columns

The title of each column is called the field title , The corresponding content is table data

Storing data ：

First step ： Create database

Code implementation ： create database Database name

The second step ： Create table

create table  Table name 
    (
         Field name     type ,
         Field name     type ,
       ....     
    )
 Copy code 

The third step ： The data in the table is analyzed increase   Delete   Change   check  

• increase ：insert into Table name ( Field 1, Field 2,...)values( value 1, value 2,...)

Be careful ： The field data added by the primary key is ignored and left blank   If the type of value is character , The value must be quoted

• Delete ： delete from Table name where Conditions

  • Condition statement ：

    • Is equal to   use  =
    • Show and   use and
    • Express or   use  or
    • If the condition field value is a character   Must be quoted

• Change ：

  update Table name set Field = The new value , Field = The new value where   Conditions

• check :

  • select * from   Table name     Query all field data in the table
  • select Field name , Field name 2 from   Table name   Query the specified field

data type ：

int   Represents integer data       char（100）   Indicates the character type     varchar（100）

Primary key ： primary key   characteristic ： Data cannot be repeated （ Have uniqueness ）

Usually in a table Number The field is the primary key Generally, the primary key is self incrementing  

How to set the primary key ：

create table  Table name 
(
   sid int primary key  auto_increment  sid  Field is     Primary key     And it's self increasing 
)
 Copy code 

php How to operate the database

Client submits data to server :

• Form transfer value name
• Hyperlink pass value <a href="xxx.php?id=213">
• ajax Passing data to the server jsonp Request interface

php Operating database steps ：

1. Select data source  localhost
2. Set up the database
3. Determine character encoding Prevent confusion code mysql_query('set names utf8')
4. To write sql sentence
5. perform sql sentence mysql_query
6. Return execution result

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Notice : come on. , Dream catcher

Learning is an ongoing process , Hold the line , There must be gains !

Accumulate over a long period , Consolidate the foundation , Enter the factory early !

It's not easy to insist , It's not easy to stick to it , you are so good !

Calm Down & Carry On!

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Read more :

Previous update review

【 Relearning JS】 Learn to consolidate the foundation series every day :

【day1】js initial 、

【day2】 Various operators 、 【day3】 data type 、 【day4】 Loop structure & Conditional statements 、 【day5】 function ( a key )、 【day6】 Scope & event 、

【day7】 object & Array method summary 、 【day8】 String method & Partial sorting 、

【day9】Math object & Packaging function 、 【day10】BOM- Browser object model 、

【day11】DOM- Document object model 、

【day12】Event The event object is first known ( One )、 【day13】Event The event object is first known ( Two )、

【day14】 Event delegation & Drag and drop principle 、

【day15】 Drag implementation & Regular initial knowledge 、 【day16】 Regular concrete method 、

【day17】cookie、 【day18】ES6、

【day19】Js Encapsulation of motion function

【day21】 Study and review in the first three weeks

【day22】 Server side and client side

More expectations on the road ... A long way to go ==-..-==