What is the type of index that is automatically built on EMP_CODE on the EMPLOYE

Question

What is the type of index that is automatically built on EMP_CODE on the EMPLOYEE table? ___________________________________.

We want to improve the speed of a query that is run to show who is assigned to each vehicle. On which table would we build the index? _______________________ and on which attribute on that table? ______________________________.

Table Name: FLEET Table Name: EMPLOYEE EMP CODE VEH ID L NAME Davolio Grubb Leverling Penn Buchanan Smith King Callaharn Dodsworth Klein Johnston Phillips Basil Sunn Barker VEH ID VEH TYPE 10 20 30 40 50 Truck-FLOATER 2 Truck Truck Truck Truck Van Line ServiceTruck 4 6 4 70 80 100 110 120 130 140 150 4

Explanation / Answer

1. Primary Index(Implicit Index as it is automatically created). Since the attribute EMP_CODE is unique and it is the primary key.

2. EMPLOYEE table. Since it also contains the driver name for the vehicle. Else , if we build the index on FLEET Table , for a vehicle, to get the driver name, you need to do a join(cross product) which takes time.

3. VEH_ID . Sincee based on this attribute , we can identify the vehicle from the veh_id

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