Relational databases implements three kinds of data integrity constraints on the three levels: column, entity and relationship. The sample SQL create table shows the implementation.
Referential Integrity Constraint
【classroom】Referential integrity constraint is one kind of integrity constraint in relational database. Each time when we break down a group of things into a number of relations, referential integrity constraint needs to be enforced for each nontrivial relationship. The constraint is implemented by creating foreign keys. The video explains the referential integrity constraint from its origin to its SQL implementation. Also some background knowledge including data modeling, entity-relationship model are mentioned. In addition, a format of writing a relational model is given in the last part of the video.
10:40 - foreign key
27:00 - the writing format of relational model
38:33 - summary
Domain & Entity Integrity Constraint
This video talks about the column and entity integrity constraints.