MySQL operation database

Create table

• Create data table

create table (if not exists)  Table name (
	 Field ,  data type   constraint condition 
	---
	[ Table constraints ]
)

create table t_goods(
 id INT,
 t_cate varchar(30),
 t_remake varchar(100)
);

• See the table

show tables

• Specify primary key PRIMARY_KEY

Single primary key

create table t_goods(
 id INT PRIMARY_KEY,
 t_cate varchar(30),
 t_remake varchar(100)
);

Single primary key

create table t_goods(
 id INT ,
 t_cate varchar(30),
 t_remake varchar(100),
 PRIMARY_KEY(id, t_cate)
);

• Foreign keys

create table t_goods(
 id INT ,
 t_cate varchar(30),
 t_remake varchar(100),
 constraint  Foreign key name  foreign key( Field ) references  surface ( Field )
);

• Non empty field

NOT NULL

• The default value is

default

• Auto increment
  auto_increment
• Specify the storage engine

create table t_goods(
id INT ,
t_cate varchar(30),
t_remake varchar(100)
) engine=InnoDB default charset set utf8mb4 collate utf8mb4_0900_ai_ci;

See the table

describe Correspondence indicates that the corresponding table information can be viewed , You can also use show create table + Table name View the corresponding table structure .

describe --

Modify data sheet

• Modify data table name

alter table A RENAME to B

• Add fields

alter table A add COLUMN  Column constraints   First/after  Field 

• Modify field name

alter table  Table name  CHANGE  Field   The new fields   New field properties 

• Change the data type of the field

alter table  Table name  modify  Field   Field properties   Field location 

• Delete field

alter table  Table name  drop  Field  

• Modify the engine

alter table  Table name  ENGINE= Engine name 

• Delete foreign key

alter table  Table name  drop foreign key --

Delete data table

drop table if exists  Table name 

A temporary table

One more temporary table is created TEMPORARY that will do

create  TEMPORARY table if not exists  Table name