MySQL Operations and notes

CREATE TABLE MyDB (
ID in auto_increment primary key is not NULL,
Price varchar (10),
Title varchar (100),
Detail varchar (500),
URL varchar (50),
seller_id varchar (50);

LOAD DATA LOCAL INFILE ' C:\\users\\administrator\\desktop\\macdb.dat '
Into TABLE macdb #表名
Fields TERMINATED by ':: '
LINES TERMINATED by ' \ n '
(id,price,title,detail,url,seller_id);

FOREIGN key
Select Hat_city.city,hat_province.province
From Hat_province
INNER join hat_city on Hat_province.provinceid=hat_city.cityid;

--Delete foreign keys
Syntax: ALTER TABLE name DROP constraint foreign KEY constraint name
Such as:
ALTER TABLE STU_PKFK_SC DROP constraint fk_s
ALTER TABLE STU_PKFK_SC DROP constraint Fk_c
--Add foreign keys
Syntax: ALTER TABLE name ADD constraint foreign KEY constraint name foreign key (column name) references Reference foreign key table (column name)
Such as:
ALTER TABLE STU_PKFK_SC
Add Constraint fk_s
Foreign KEY (SNO)
References stu_pkfk_s (SNO)
Go
--Delete primary key
Syntax: ALTER TABLE name DROP constraint PRIMARY KEY constraint name
Such as:
ALTER TABLE stu_pkfk_s DROP constraint pk_s
Go
--Increase the primary key
Syntax: ALTER TABLE name ADD constraint PRIMARY KEY constraint name primary key (column name)
ALTER TABLE stu_pkfk_s ADD constraint pk_s primary key (SNO)
Go

MySQL Operations and notes