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UWA week 40 (2nd semester, week 10) ↓

Can we merge / split tables or move items (both)

10:59pm Tue 1st Oct, Hafiz A.

while I was putting dummy data in each of the table to verify - if the table is in 3NF - if the Primary Key need to be changed; for Vehicle Type table, I can see Make & Model are taken as composite primary keys, but I can use duplicate values in each of these columns. e.g. below is a table I generated Make Model Doors Body Trim Fuel Toyota Camry 4 Sedan Sport Petrol Toyota Camry 4 Sedan L Hybrid Honda City 4 Sedan Aspire Hybrid Honda Civic 4 Hatch Sport Hybrid Considering the company may have multiple cars of same make/mode/doors...….., the table is not in even 1NF. I can solve it by 1- adding a unique identifier as a serial number in this table and use it with PK or 2- merge Vehicle table which has three attributes regNum / FleetNum / Colour with vehicle type. regNum / FleetNum both are unique and qualify to be a PK of the merged table. Can you please guide which approach I should take? if we are allowed to merge / split / move attributes around from the ERD model, I would prefer to merge two tables rather than adding additional attributes. I did consider using subclass / superclass however for the sake of implementation in SQLITE, merging seems to be best option.

Can we merge / split tables or move items (both)

11:39am Thu 3rd Oct, Adam W.

When there isnt a suitable natural key present, you would normally make a surrogate key like a unique ID number, so approach #1 would be best. "Hafiz Ahmad" <24*3*5*6@s*u*e*t*u*a*e*u*a*> wrote:

> while I was putting dummy data in each of the table to verify > - if the table is in 3NF > - if the Primary Key need to be changed; > > for Vehicle Type table, I can see Make & Model are taken as composite primary keys, but I can use duplicate values in each of these columns. e.g. below is a table I generated > > Make Model Doors Body Trim Fuel > Toyota Camry 4 Sedan Sport Petrol > Toyota Camry 4 Sedan L Hybrid > Honda City 4 Sedan Aspire Hybrid > Honda Civic 4 Hatch Sport Hybrid > > Considering the company may have multiple cars of same make/mode/doors...….., the table is not in even 1NF. I can solve it by > > 1- adding a unique identifier as a serial number in this table and use it with PK or > 2- merge Vehicle table which has three attributes regNum / FleetNum / Colour with vehicle type. regNum / FleetNum both are unique and qualify to be a PK of the merged table. > > Can you please guide which approach I should take? if we are allowed to merge / split / move attributes around from the ERD model, I would prefer to merge two tables rather than adding additional attributes. > > I did consider using subclass / superclass however for the sake of implementation in SQLITE, merging seems to be best option.

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