Home Database Mysql Tutorial mysql数据库学习――4,完整性约束_MySQL

mysql数据库学习――4,完整性约束_MySQL

Jun 01, 2016 pm 01:32 PM
mysql database

bitsCN.com

mysql数据库学习——4,完整性约束

 

主键

create table feng(teamno int not null,playerno int not null,pision char(6) not null,primary key(teamno))create table feng(teamno int not null primary key ,playerno int not null,pision char(6) not null,)
Copy after login

复合主键

create table feng(teamno int not null,playerno int not null,pision char(6) not null,primary key(teamno,playerno))
Copy after login

替代键(候选键)

create table feng(teamno int not null primary key ,playerno int not null,pision char(6) not null,unique(playerno))create table feng(teamno int not null primary key ,playerno int not null,pision char(6) not null,unique(playerno,pision))
Copy after login

外键(在innoDB中使用)

外键声明包括三个部分

1,那个列或列组合是外键

2,指定外键参照的表和列

3,参照动作[cascade(级联操作),restrict(拒绝操作),set null(设为空),no action,set default]

如果没有指定参照动作默认是

on update restricton delete  restrictcreate table feng(teamno int not null primary key ,playerno int not null,pision char(6) not null,foreign key(pision)references othertable   (column)on update restrictunique(playerno))check完整性约束create  table players (playerno int not null, sex   char(1) not null,         check (sex in (&#39;m&#39;,&#39;f&#39;)))create  table players (playerno int not null,birth_date  date, sex   char(1) not null,         check (sex in (&#39;m&#39;,&#39;f&#39;))joined smallint not null,             check (year(birth_date)<joined),             check (joined<1880),)create  table players (playerno int not null,birth_date  date, sex   char(1) not null,          check (sex in (select sex from wholetab))
Copy after login

 


bitsCN.com
Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot Article Tags

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

PHP's big data structure processing skills PHP's big data structure processing skills May 08, 2024 am 10:24 AM

PHP's big data structure processing skills

How to optimize MySQL query performance in PHP? How to optimize MySQL query performance in PHP? Jun 03, 2024 pm 08:11 PM

How to optimize MySQL query performance in PHP?

How to use MySQL backup and restore in PHP? How to use MySQL backup and restore in PHP? Jun 03, 2024 pm 12:19 PM

How to use MySQL backup and restore in PHP?

How to insert data into a MySQL table using PHP? How to insert data into a MySQL table using PHP? Jun 02, 2024 pm 02:26 PM

How to insert data into a MySQL table using PHP?

How to fix mysql_native_password not loaded errors on MySQL 8.4 How to fix mysql_native_password not loaded errors on MySQL 8.4 Dec 09, 2024 am 11:42 AM

How to fix mysql_native_password not loaded errors on MySQL 8.4

How to use MySQL stored procedures in PHP? How to use MySQL stored procedures in PHP? Jun 02, 2024 pm 02:13 PM

How to use MySQL stored procedures in PHP?

How to create a MySQL table using PHP? How to create a MySQL table using PHP? Jun 04, 2024 pm 01:57 PM

How to create a MySQL table using PHP?

Detailed tutorial on establishing a database connection using MySQLi in PHP Detailed tutorial on establishing a database connection using MySQLi in PHP Jun 04, 2024 pm 01:42 PM

Detailed tutorial on establishing a database connection using MySQLi in PHP

See all articles