Relationships

“ 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

Data Redundancy idnameDobphoneclassTutorRoom 356Jess3 Mar BMr Noggin56 412Hamad12 Nov XMr Noggin56 459Sita9 Jan BMs Take18 502James10 March BMr Noggin56 This is a flat file database, boo hiss!!! The problem is that we have redundancy

How to solve the issue  Simply take the data out  Make another table idnameDobphoneclassTeacher 356Jess3 Mar B1 412Hamad12 Nov X1 459Sita9 Jan B2 502James10 March B1 idtutorroom 1 Mr Noggin56 2 Ms Take18 Students Teachers

Different types of relationship  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 Table 1 Table 2 Important Fact This can never be made, as the database wont allow it

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 Extension Challenge Try and find the problem with using a 1 to many relationship