relationships and referential integrity

HideShow resource information
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

Comments

No comments have yet been made

Similar ICT resources:

See all ICT resources »See all Data and Information resources »