如何建立兩個表格之間的父母子女關係

Question

我有2個表格課程主任和課程主題在課程大師我有2列課程代碼和課程名稱和課程主題我有課程代碼和主題代碼。我的目標是如果我刪除課程代碼當然掌握它不應該刪除，如果我更新它應該得到更新，並反映在課程subject.pls告訴我如何寫這個查詢。

我當然主表結構

# Name Type Collation Attributes Null Default Extra Action 
    1 id int(11)   No None   Change Change Drop Drop Browse distinct values Browse distinct values Primary Primary  Unique Unique Index Index Spatial Spatial Fulltext Fulltext 
    2 course_code varchar(255) latin1_swedish_ci  No None   Change Change Drop Drop Browse distinct values Browse distinct values Primary Primary Unique Unique Index Index Spatial Spatial Fulltext Fulltext 
    3 course_name varchar(255) latin1_swedish_ci  No None   Change Change Drop Drop Browse distinct values Browse distinct values Primary Primary  Unique Unique Index Index Spatial Spatial Fulltext Fulltext 

課程學科結構

Name Type Collation Attributes Null Default Extra Action 
1 id int(11)   No None AUTO_INCREMENT Change Change Drop Drop Browse distinct values Browse distinct values Primary Primary Unique Unique Index Index Show more actions More 
2 course_code varchar(255) latin1_swedish_ci  No None   Change Change Drop Drop Browse distinct values Browse distinct values Primary Primary  Unique Unique Index Index Show more actions More 
3 subject_code varchar(255) latin1_swedish_ci  No None   Change Change Drop Drop Browse distinct values Browse distinct values Primary Primary  Unique Unique Index Index Show more actions More 

Answer 1

CREATE TABLE Course 
(
id int NOT NULL, 
name varchar(255) NOT NULL, 
code varchar(255) NOT NULL, 
PRIMARY KEY (id) 
); 

CREATE TABLE Subject 
(
id int NOT NULL, 
code varchar(255) NOT NULL, 
CourseId int NOT NULL, 
PRIMARY KEY (id), 
FOREIGN KEY (CourseId) REFERENCES Course(id) 
); 

Answer 2

那看來你需要建立表之間的關係。

ALTER TABLE 'master' ADD PRIMARY KEY ('course_code'); 
ALTER TABLE 'subject' ADD FOREIGN KEY ('course_code') REFERENCES 'master' ('course_code');