In a vehicle service database, the requirement to find registration numbers and owner names of vehicles that have never undergone servicing can be solved efficiently using SQL queries. This problem is based on the relational database concepts of tables, primary keys, foreign keys, joins, subqueries, and set-based operations. The main objective is to identify all vehicles recorded in the vehicle table for which no corresponding service record exists in the service or servicing table. Assume that the database contains a `Vehicle` table and a `Service` table. The `Vehicle` table stores information about vehicles and their owners, while the `Service` table stores details of services performed on vehicles. A possible structure of the `Vehicle` table is: ```sql Vehicle( Registration_No, Owner_Name, Vehicle_Model, Vehicle_Type ) ``` The `Service` table may have the following structure: ```sql Service( Service_ID, Registration_No, Service_Date, Service_Type, Service_Cost ) ``` Here, `Registration_No` in the `Vehicle` table uniquely identifies each vehicle and can act as the primary key. The same attribute in the `Service` table can act as a foreign key because it refers to the registration number of the vehicle that received servicing. The phrase “vehicles that have never undergone servicing” means that there must be no record in the `Service` table corresponding to the registration number of the vehicle. Therefore, the problem is essentially an example of finding records in one table that do not have matching records in another table. One straightforward method is to use the `NOT IN` operator with a subquery: ```sql SELECT Registration_No, Owner_Name FROM Vehicle WHERE Registration_No NOT IN (SELECT Registration_No FROM Service); ``` The inner query retrieves all registration numbers of vehicles that have undergone at least one service. The outer query then selects vehicles whose registration numbers are not present in that list. Thus, only vehicles that have never appeared in the `Service` table are displayed. For example, suppose the `Vehicle` table contains: ```text Registration_No Owner_Name MH12AB1234 Raj Kumar DL01CD5678 Amit Sharma UP32EF9012 Neha Singh KA05GH3456 Priya Verma ``` Suppose the `Service` table contains: ```text Service_ID Registration_No 101 MH12AB1234 102 UP32EF9012 103 MH12AB1234 ``` The vehicles `MH12AB1234` and `UP32EF9012` have service records. The registration numbers `DL01CD5678` and `KA05GH3456` do not appear in the `Service` table. Therefore, the output of