relationships and referential integrity
- Created by: Thegirlwhoknewtoomuch - Team GR
- Created on: 25-05-13 13:16
View mindmap
- relationships and referential integrity
- relationships
- link entities from one table with entities in another table
- one to one
- one record in a table is only able to link with one record in another table
- E.g. one company car for one employee
- one to many
- one record in a table is linked with many records in another table
- E.g. one library member can borrow many books
- many to many
- many record in a table can be linked with many records in another table
- E.g. many products can be brought by many customers
- referential integrity
- every foreign key has a matching value to the corresponding primary key
- makes sure records related to another record aren't deleted
- makes it impossible to enter a reference to a link that doesn't exist
- relationships
Similar ICT resources:
Teacher recommended
Comments
No comments have yet been made