QUESTION $3$

$($a$)$ Explain the function of the two main types of keys in relational databases. Primary Key and Foreign key.

$($b$)$ The following is an extract of data from an online movie database. Convert the table into First Normal form:

$\backslash$table$[[\backslash$table$[[$Customer$],[$ID$]],\backslash$table$[[$Customer$],[$Name$]],$Movies rented,Director$],[1,$John Jones,$\backslash$table$[[$Yesterday$],[$Aladdin$]],\backslash$table$[[$Danny Boyle$],[$Guy Ritche$]]],[2,$Mark Smith,$\backslash$table$[[$Captain Marvel$],[$Rocketman$]],\backslash$table$[[$Anna Boden$],[$Dexter Flecther$]]],[3,$Stella Murphy,$\backslash$table$[[$A star is born$],[$Incredibles $2],[$Toy story $4]],\backslash$table$[[$Bradley Cooper$],[$Brad Bird$],[$Josh Cooley,$],[$Jonas Rivera$]]]]$

$($c$)$ Based on the data in the table, explain how you would restructure the table into $3NF.$ Mention any interim stages of normalisation if they exist. The normalised data is not required, only the normalised structures.