{"id":465,"date":"2023-01-25T13:39:50","date_gmt":"2023-01-25T13:39:50","guid":{"rendered":"http:\/\/learnlearn.uk\/ibcs\/?page_id=465"},"modified":"2023-01-25T13:39:50","modified_gmt":"2023-01-25T13:39:50","slug":"referential-integrity","status":"publish","type":"page","link":"https:\/\/learnlearn.uk\/ibcs\/referential-integrity\/","title":{"rendered":"Referential Integrity"},"content":{"rendered":"
\n

Referential Integrity<\/h2>\n
\n\n

Referential Integrity<\/h3>\n

With a relational database tables are linked together with relationships. This means that if you alter the contents or structure of a table (such as removing an entry or changing a column\u00a0 name) this can have an effect on other tables. If this happens then steps must be taken\u00a0 to maintain referential integrity.<\/p>\n\n<\/div>

Example<\/h2>\n
\n\n

Example – Pupil and Class table<\/h4>\n

In the example below we have 2 tables. Each pupil is a member of a class the classID in the pupil table is a foreign key from the class table. This means that the integrity of the pupil table is dependent on the class table.<\/p>\n

\"\"<\/a><\/p>\n\n<\/div>

Integrity Compromised<\/h2>\n
\n\n

Referential Integrity compromised<\/strong><\/p>\n

If you alter the contents or structure of the class table then steps must be taken to maintain the referential integrity in the pupil table.<\/p>\n

\"\"<\/a>

Here class 2 has been removed which has had an effect on the pupil table<\/p><\/div>\n\n<\/div>

Maintain Integrity<\/h2>\n
\n\n

Maintaining Integrity<\/h3>\n

 <\/p>\n

Option 1\u00a0 –\u00a0 Use a null value<\/strong><\/p>\n

\"\"<\/a>

Here the referential integrity has been restored by setting the class to a null value<\/p><\/div>\n

 <\/p>\n

Option 2 – Change the ClassID to a valid class<\/strong><\/p>\n

\"\"<\/a><\/p>\n\n<\/div>

Resources<\/h2>\n
\n\n

Teacher Presentation<\/a><\/p>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n<\/div><\/div>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

Referential Integrity With a relational database tables are linked together with relationships. This means that if you alter the contents or structure of a table (such as removing an entry or changing a column\u00a0 name) this can have an effect on other tables. If this happens then steps must be taken\u00a0 to maintain referential integrity.… Read More »Referential Integrity<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"neve_meta_sidebar":"","neve_meta_container":"","neve_meta_enable_content_width":"","neve_meta_content_width":70,"neve_meta_title_alignment":"","neve_meta_author_avatar":"","neve_post_elements_order":"","neve_meta_disable_header":"","neve_meta_disable_footer":"","neve_meta_disable_title":""},"yoast_head":"\nReferential Integrity - IB Computer Science<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/learnlearn.uk\/ibcs\/referential-integrity\/\" \/>\n<meta property=\"og:locale\" content=\"en_GB\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Referential Integrity - IB Computer Science\" \/>\n<meta property=\"og:description\" content=\"Referential Integrity With a relational database tables are linked together with relationships. 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