What are the requirements of mysql foreign key constraints

What are the requirements of mysql foreign key constraints, many novices are not very clear about this, in order to help you solve this problem, the following editor will explain for you in detail, people with this need can come to learn, I hope you can gain something.

1. Establish a foreign key on the table, and the primary table should exist first.

2. A table can establish multiple foreign key constraints.

3. The foreign key column of the slave table must point to the primary key column of the primary table.

4. the foreign key column of the slave table can be different from the column name referenced by the master table, but the data type must be the same.

Example

Mysql > show create table students\ gateway * 1. Row * * Table: studentsCreate Table: CREATE TABLE `students` (`id` int (11) NOT NULL AUTO_INCREMENT, `uid` int (11) NOT NULL, `name` varchar (6) NOT NULL, PRIMARY KEY (`id`), KEY `uid` (`uid`) Is it helpful for CONSTRAINT `students_ibfk_ 1` FOREIGN KEY (`uid`) REFERENCES `class` (`xuehao`) ENGINE=InnoDB DEFAULT CHARSET=utf8 to read the above content? If you want to know more about the relevant knowledge or read more related articles, please follow the industry information channel, thank you for your support.