Write table of MySQL Foundation (create table)

Tools

On the market SQL There are many visualization tools , I usually use these two .

Of course ,IDEA It also integrates the database visualization function . In addition to these , also DBeaver、SQLyog wait .

I prefer DataGrip, I'll use this to demonstrate . But this interface doesn't have Navicat It's beautiful , However, I feel that the function is much more powerful .

Write a watch

here , I've created a Demo database .

Let's first understand the syntax of creating tables .

Create table

USE Demo;
#  The grammar is as follows 
# CREATE TABLE [IF NOT EXISTS]  Table name ( Field contents )
CREATE TABLE IF NOT EXISTS class(
    Id INT(4) COMMENT 'ID Number ',
    Name VARCHAR(10) COMMENT ' full name '
);

IF NOT EXISTS You can omit it .

CREATE TABLE class(
    Id INT(4) COMMENT 'ID Number ',
    Name VARCHAR(10) COMMENT ' full name '
);

remember CREATE TABLE Used to create tables .

Create fields

() Inside are the fields of the table , The format of the written field is as follows .

#  Field name   value type  COMMENT ' Field notes '
Id INT(4) COMMENT 'ID Number ',
Name VARCHAR(10) COMMENT ' full name '

• If the value type is to be set, the length , We can connect... At the back (), Fill in the length value .
• COMMENT Keywords are the corresponding notes used to create fields , Remarks must be followed by .

Field constraints and attribute settings

We can set constraints and properties for fields through some keywords .

Id INT(4) COMMENT 'ID Number ' PRIMARY KEY ,
id INT(4) COMMENT 'ID Number ' PRIMARY KEY AUTO_INCREMENT NOT NULL  UNIQUE KEY 

such as ,PRIMARY KEY Keyword can set the field as the primary key .

Variable position ！ The corresponding syntax format is enough , Field data type [ Field properties | constraint ] [ Indexes ] [ Field notes ].

For these constraints , If you need to know the detailed function , Please go to the browser to view , Hey ！

Common data types

value type

The date type

String type