MySQL Tutorial / Examples of Common Queries / Using Foreign Keys 7.6 Using Foreign Keys MySQL supports foreign keys, which permit cross-referencing related data across tables, and foreign key constraints, which help keep the related data consistent. ...
To disable foreign key checks, you use the following statement: 1 SET foreign_key_checks = 0; And of course, you can enable it using the statement below: 1 SET foreign_key_checks = 1; In this tutorial, we have covered a lot about MySQL foreign key. We also introduced you to some...
foreign key(repo_id) references repo_table(repo_id)) 参考 【1】w3school关于mysql的专题讲解 http://www.w3school.com.cn/sql/sql_foreignkey.asp 【2】MySQL C API programming tutorial http://zetcode.com/tutorials/mysqlcapitutorial/ 【3】 对外键的使用示例,很不错 http://hi.baidu.com/wangzhiqing...
foreign key(repo_id) references repo_table(repo_id)) 参考 【1】 w3school关于mysql的专题讲解 http://www.w3school.com.cn/sql/sql_foreignkey.asp 【2】 MySQL C API programming tutorial http://zetcode.com/tutorials/mysqlcapitutorial/ 【3】 对外键的使用示例,很不错 ...
employees table to reflect the reporting structure between employees i.e., each employee reports to anther employee and an employee can have zero or more direct reports. We have a specific tutorial on the self-join to help you query data against this kind of ...
foreign key(repo_id) references repo_table(repo_id)) 参考 【1】w3school关于mysql的专题讲解 http://www.w3school.com.cn/sql/sql_foreignkey.asp 【2】MySQL C API programming tutorial http://zetcode.com/tutorials/mysqlcapitutorial/ 【3】 对外键的使用示例,很不错 ...
The plugin created in this tutorial gets around this problem by using the fact that a naming convention is often used for foreign keys: tablename_primarykeyname. Using this convention, foreign keys can automatically be created after a database is reverse engineered, which will result in ...
foreign key(repo_id) references repo_table(repo_id)) 参考 【1】w3school关于mysql的专题讲解 http://www.w3school.com.cn/sql/sql_foreignkey.asp 【2】MySQL C API programming tutorial http://zetcode.com/tutorials/mysqlcapitutorial/ 【3】 对外键的使用示例,很不错 ...
ExampleGet your own SQL Server SELECT*FROMCustomers; Try it Yourself » Click on the "Try it Yourself" button to see how it works. MySQL Exercises Many chapters in this tutorial end with an exercise where you can check your level of knowledge. ...
完整性约束包括:not null、auto_increment、primary key、foreign key(外码)referrences 参照表(主码)、unique、check() 等; 08、删除MySQL数据表 drop table 表名;//如 drop table course; 09、插入数据 insert into 表名 ( field1, field2,...fieldN ) ...