Database creation, addition, deletion, modification and query

The database is easy to operate

// View version number

select version();

// View all local databases

show databases; 

// Write what you check

select  ‘xxxx’;

// Switch database

use test;

// Look at all the tables

show tables;

// sign out

Exit

Select   Inquire about

Insert insert data

Update Update data

Delete Delete data

Drop Delete table

Create Create table

SQL classification :

DCL Data control language (Data Control Language)

Represent keyword :grant,revoke.

DDL Data definition language (Data Definition Language)

Represent keyword :create ,drop,

DML Data operation language (Data Manipulation Language)

Represent keyword :insert,delete,update

DQL Data query language (Data Query Language)  

Represent keyword :select

TCL Transaction control language (Transactional Control Language)

Represent keyword :commit ,rollback;

Create database

grammar ：create table  Table name (

Name type ,

Name type ,

);

CREATE TABLE `student_info1` (
  `student_name` varchar(255) DEFAULT NULL,
  `student_age` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE if not exists `student_info` (
  `student_name` varchar(255) DEFAULT NULL,
  `student_age` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
CREATE TABLE `student_info3` (
  `student_name` varchar(255) DEFAULT NULL,
  `student_age` int(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Insert

grammar

insert into Table name ( Name 1, Name 2) values ( value 1, value 2);

insert into student_info (student_name,student_age) values (' Two dogs ',23);

Update

grammar

update   Table name set Name 1= value , Name 2= value  where Name = value ;

update student_info set student_age=66 where student_name=' Two dogs ';

Delete

grammar

delete from  Table name where Name = value ;

delete from student_info where student_name=' Two dogs ';

select:

grammar

select Column qualification from Table limit where Row qualification

select student_name from student_info where student_age=23;

select * from student_info;