1 / 6

Relationships

Relationships. “ S ituation that exists between two relational database tables ”. It stop the need for repeating data A llows the database to be smaller in size Makes it easier to update, add and delete information It also makes searching the database easier. Data Redundancy.

zizi
Download Presentation

Relationships

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Relationships

  2. “Situation that exists between two relational database tables” • It stop the need for repeating data • Allows the database to be smaller in size • Makes it easier to update, add and delete information • It also makes searching the database easier

  3. Data Redundancy This is a flat file database, boo hiss!!! The problem is that we have redundancy

  4. How to solve the issue • Simply take the data out • Make another table Students Teachers

  5. Different types of relationship Table 1 Table 2 • One to One • A persons credit check • One to Many • A teacher and students • Many to Many • Online orders Table 1 Table 2 Table 1 Table 2 Important Fact This can never be made, as the database wont allow it

  6. The Task • You need to design a second table in your ERD for actors • Then you need to build the table • Add some actors into your table and link them with films. Extension Challenge Try and find the problem with using a 1 to many relationship

More Related