Basic MySQL operations

MySQL Basic function

One . Basic operation

1. Access to database

Mysql -uroot -p Enter the database password after entering

 

2. Query the database

show databases;

 

3. Create database student

create database student;

 

4. Delete database

drop database  Database name

 

5. Using a database student

use student;

 

6. Create table

create table aa(id int(10),name varchar(20),city varchar(20));

 

7. Write data

insert into aa(id,name,city) values(1,"wang","beijing");

 

8. Query table data

select * from aa;  Query all the data

 select id,name from aa;  Inquire about id and name Field

select city from aa where name="wang"; Inquire about name by wang Of city

 

9. Modifying data

update aa set name="song" where id=1;

 

10. Delete data

delete from aa where id=1;

 

• Advanced operation

1. order by usage

 select *from aa order by id desc;  according to id Sort from high to low

 

 select id,name from aa order by 1; With id Sort

 

select id,name from aa order by 2; With name Sort

 

2.limit usage

Limit M,N

// Says from the first M+1 Data starts , Query down in sequence N Data

Limit M

// Indicates before query M Data

select * from aa limit 2,2;  Query table 3,4 Data

 

select id,name from aa limit 1,3;  Inquire about id name Of 234 Data

 

3.union select Usage of

select * from aa union select 1,2,3;  Query three columns and display at the bottom of each column

 

When the columns of the table and the columns of the query are inconsistent , You're going to report a mistake , It will also expose the value of the field

 

4.union select combination information_schema database

MySQL5.0 There is a version called information_schema The database of , It stores all the information in the database , It's about MySQL Information about all other databases maintained by the server . Such as database name , Table of database , Data type and access right of table column . and 5.0 There is no .

show databases;

 

select schema_name from information_schema.schemata;

The execution result of two sentences is the same

 use student;

show tables;

 

 select table_name from information_schema.tables where table_schema='student';

 

Found the same .